'Sexology is simply the science of studying sex. It's an interdisciplinary subject. It can include any subjects you have in the world, as long as they relate to sex, such as erotic art, which you can study in a scientific way. And then you can have sociology of sex, psychology of sex, sexual medicine, sexual literature, whatever.' The World Association for Sexology holds its congress every two years. This one, says its president, Professor Eli Coleman, is titled Sexuality In The New Millennium.

'This congress will be the first held on Chinese soil,' he says. 'We will have the opportunity to see how sexology is studied in a culture which encompasses over one-quarter of the world's population. What we can contribute and learn from this congress will certainly shed light on what we should and could do in shaping our sexuality in the coming century.' The paradox of this sex-fest is that many of its luminaries are so, well, unsexy. The University of Hong Kong's Dr Ng, despite his unofficial title of 'Dr Sex', is a bookish chap with rumpled grey slacks and a comb-over. A trawl through the local organising committee reveals the presence of renowned raunchsters like Peggy Lam Pei Yu-dja, Rita Fan Hsu Lai-tai and Dr Leong Che-hung - who, admittedly, sports a sleek Valentino-style centre parting.

Still, any lack of sex appeal on the part of the organisers will not stop the convention centre resounding to the many and varied sounds of sex. The packed programme features dozens of speakers on myriad topics, ranging from the odd to the otiose, the banal to the bizarre - everything you ever wanted to know about sex, in fact, but were afraid to ask.

Keynote speakers include Danish sexologist Gorm Wagner, who will focus on the Viagra revolution, Chinese Medical Association honorary president and 'father of sexology in modern China' Wu Jieping and German Professor Erwin Haeberle, who promises to address himself with gusto to the intriguing problems of sex and the Internet with a 'live demonstration'.

And then there is the professor who sounds like she was born to be a sexologist - Beverly Whipple, author of The G Spot And Other Recent Discoveries About Human Sexuality. Her address is titled Beyond The G Spot: Where Do We Go From Here? The H Spot, perhaps? Other lectures and workshops on offer include: Love And Lust In Art Form, Or What Is A Sexologist Doing At The Opera?; Intersexuality - Different Types, Ambiguous Genitals And Recommendations For Management; Re-search (sic) In Kama Sutra - Ancient But Modern; Marriages For The Millennium - Puritans And Pagans View The Future; Promiscuous Husbands And Loyal Wives - The Moral Order Among Hong Kong Chinese; How The Clitoris Got Lost; Promotion Of Copulatory Behaviour In Inexperienced Castrated Male Rats; and Studies Of Ejaculatory Latency And Penile Vibratory Threshold With SS-Cream In Patients With Lifelong Premature Ejaculation.

Open to the public from 9am to 7pm, August 24 to 27, will be a Sexology Exhibition. For a $20 admission fee (under 18s not allowed), you can feast your eyes on ancient and modern Chinese sexual paintings (originals and reproductions), posters, sexual health products, erotic stamps and Chinese sexual antiques (that's furniture, not the Politburo).

Sexology is an oft-misunderstood and maligned science, says Dr Ng, and a difficult one to get people to take seriously, especially when the time comes to apply for research grants. This is understandable.

Sexologist: I need $500,000 to conduct a comprehensive study on the long-term effects of excessive nipple-clamp use in gay leather bars.

University Grants Committee: Get out of here.

And then there is the minefield of bad puns and double entendres upon revealing your chosen profession, not to mention being mistaken regularly for a gigolo or a gynaecologist.

The modern-day sexologist's life is not an easy one but it does have its high points, such as, in Dr Ng's case, successfully lobbying to hold the congress in Hong Kong.

'I've been trying to get it here for about 10 years,' he says. 'It has taken a lot of effort and support. I collected letters from a range of sexologists in China.' Despite communist rule and the ardour-dampening one-child policy, the mainland, apparently, is teeming with sexologists. 'The Shanghai Sex Education Association has been established for more than 13 or 14 years. Then there is also the China Sexology Association, and in nearly every big city in China there is at least one sex education or sexology group,' Dr Ng says. 'Sexology is quite a well-established subject in China and it's taught as a postgraduate degree in some universities.

'In fact, I would say they are more open about sex on the mainland than in Hong Kong. China has a long history not only in erotica but in the study of sex. There is the first sex manual in human civilisation, the book of the Su-Nu-Ching. It was written 2,000 years ago.

'It's a Kama Sutra-type of thing, not illustrated but very explicit. It was written during the Han Dynasty. It was only after the Mongolian invasion that civilisation was weakened and people became a bit more reserved about sex.' Dr Ng hopes the congress will prove the catalyst for an explosion of interest in sexology throughout the region.

'Although there are many Chinese sexologists, this will be the first time for many of them to have contact with so many international sexologists.

'It's also a chance for the rest of the world to see what and how sexologists practise in China. So I think it's a very good opportunity for an exchange of knowledge.' What about other sorts of exchanges, what with all these people sitting around talking about sex for a week? Are World Congresses on Sexology hothouses of romance and torrid affairs? Dr Ng, who has attended most of the congresses, just laughs.

'We are very serious people, just like any other congress. You see, that's the problem. A lot of people have a lot of imagination about the sexology congress.

'Sexologists are a little bit less solemn, they're open people, otherwise they wouldn't be sexologists. But we are just as serious about our work as people in any other discipline.' The study of sex dates back to at least the ancient Greeks, when philosophers like Plato and Aristotle made extensive observations on sexual responses, dysfunctions, legislation and ethics. And then there was Hippocrates and his, er, seminal work, On Semen.

Sexology as a systematic academic discipline, however, was not born until 1907 when dermatologist and sexual therapist Iwan Bloch introduced it in Berlin. He proposed a theoretical, scientific and objective approach to studying sex, as opposed to erotic writings such as the Kama Sutra which were intended to guide the reader to subjective experiences.

Bloch, a man of enormous erudition, spoke several languages and possessed a personal library of more than 40,000 volumes, none of which were Playboy or Hustler. He knew from his readings that many supposedly pathological and degenerate sexual behaviours had always existed in many parts of the world, and he became convinced the medical view of sexual behaviour was short-sighted.

His ground-breaking 1907 study, Das Sexualleben Unserer Zeit (The Sexual Life Of Our Time), provoked a revolution. He was, he wrote, 'convinced that the purely medical consideration of the sexual life, although it must always constitute the nucleus of sexual science, is yet incapable of doing full justice to the many-sided relationships between the sexual and all the other provinces of human life'. Rather, sexual studies should conflate 'all other sciences - general biology, anthropology and ethnology, philosophy and psychology, the history of literature and the entire history of civilisation'.

His new concept was eagerly embraced by Magnus Hirschfeld, who had founded the first organisation for homosexual rights in Berlin in 1897.

Hirschfeld became editor of the first journal of sexology, Zeitschrift Fur Sexualwissenschaft, which, in its first issue, contained an article by another rising star of the psycho-sexual arena, Sigmund Freud.

After World War II, sexology experienced a renaissance in America through the efforts of Alfred Kinsey. His experience as a zoologist turned out to be the perfect grounding for studying sex in humans and he churned out two monumental studies, Sexual Behaviour In The Human Male (1948) and Sexual Behaviour In The Human Female (1953). A decade later came the team of William Masters and Virginia Johnson, with their works on the treatment of sexual dysfunction.

This brings us to the sexologist of today, and back to the office of Dr Ng. Tucked away at the back of Queen Mary Hospital, it is hardly a temple of lust and dionysian abandon. The only hints as to his speciality are the shelves of well-thumbed sex-themed tomes and a model of a Long March rocket which rears phallically from his desk.

'Nowadays sexologists aren't so concerned with surveys, such as Kinsey's,' he says. 'The focus has switched to the genetics of sex, biological factors, drugs, surgery.

'We are trying to discover how genes determine a person's sexual orientation and patterns.' A moral and ethical minefield, he agrees, if ever there was one.

Dr Ng is also heavily involved in sex education, which he believes is still sadly lacking in Hong Kong. 'Sex education is far behind the needs of the young people. It starts too late; it's not taught well.

'The Education Department says it starts sex education in primary school and even kindergarten. Well, you can tell someone you're a girl and you're a boy, but that's not sex education.

'Hopefully by bringing the World Congress on Sexology to Hong Kong, we will promote sex education and stimulate people to look more seriously into sex.' Unlike many parents, Dr Ng is not alarmed by the proliferation of hardcore pornography on the Internet.

'Really, there is no way of stopping kids from getting access to sexual information of whatever type. Even the nasty stuff. So it just means that sex education is even more important, that we as parents and teachers must, at an early stage, give them the knowledge and method of how to receive this information and also to have a critical mind.

'I'm not worried about having kids exposed to this stuff. What worries me is that after they've been exposed to this stuff, nobody will answer their questions or listen to their opinions.

'My children are all grown up now. I taught them about sex very early on, I let them see whatever they liked to see. I let them see adult movies when they were six, or eight or nine.' This did not, he says, turn them into rampaging deviants. 'My son is now 24 and I don't think he's had any real sexual intercourse experience yet. My girl is 22 now. Of course I cannot be sure whether she has had sex yet, but at least she has not got pregnant or caught any sexually transmitted diseases.' You might imagine that becoming a sexologist takes the mystery and fun out of sex, reducing something miraculous to the level of dusty tomes and turgid theories. Not so, says Dr Ng. 'If you cook a lot and work with all the ingredients, you can still eat a lot and enjoy your food. You get gynaecologists who examine genitalia every day and still have a sexual life.

'The thing is sex is a human instinct like food. So the more you know about it, the more you know how to enjoy it. I've been in the field a long time. And I enjoy sex now just as much as I did when I was a teenager.' He pauses, for a bit of Beavis and Butthead-esque sniggering. 'In fact, I enjoy it more than when I was young, because I know more, I know how to do it better.' So what are the enemies of good sex? 'There are many: stress, overwork, lack of communication, being selfish and egotistic, people being too practical, no time to fantasise, no time for adventure. Also, some religions are obviously very anti-sexual and they have a big influence on people.' He says the advent of the millennium gives this congress extra cachet. 'It's a time for sexologists to review what we have achieved and lost in the past millennium. What has been lost? I think the past millennium has seen the rise of many sexual inhibitions in both the East and West.

'It's only in this century that scientific advancements and sexual freedom have happened. But there is still a big battle to be fought. And we are still fighting.'