The prevalence of sexually transmitted diseases (STDs) diagnosed in men attending an outpatients' clinic for gay men from 1983 to 1997 and the results from a questionnaire survey concerning sexual behaviour conducted in 1994-96 are reported, The prevalence of gonorrhoea and chlamydia has decreased during the period, although in 1997 there was a micro-epidemic of gonorrhoea in gay men in Gothenburg. The results indicate that the reservoir of syphilis and hepatitis B in the gay population was eradicated during the early 1980s, Of altogether 1808 HIV tests performed, 3.0% (n = 55) were positive. In the questionnaire, the majority claimed they had sufficient knowledge on how HIV is transmitted, while 11.3% stated that they lacked that knowledge, Half of the patients stated that they had a steady sexual partner, Starting a new relationship was the most common reason (69%) for HIV screening, The use of condoms in anal and oral sex was 88% and 31%, respectively. Of those practising anal ses, 4% stated that they never used a condom. The prevalence of STDs has decreased in this period of time and safer sex is fairly well accepted, but the results also tell us that there is still a need for dedicated clinics like ours.