Of 6125 women attending an STD clinic from 1988 to 1991, 5365 (88%) were tested for vaginitis of whom 97 (1.8%) had trichomoniasis, 945 (17.6%) had candidiasis, 734 (13.7%) had bacterial vaginosis and 3628 (67.6%) were free of vaginal infection. Dual infections occurred in 49 (0.9%) patients. Independent predictors for trichomoniasis by multivariate analysis were being pregnant (odds ratio (OR) = 2.4), having vaginal discharge or dysuria (OR = 4.7), being Aboriginal (OR = 4.3), being Asian (OR = 5.0), being unemployed (OR = 2.1) or tattoed (OR = 1.9). Many factors, including use of oral contraception (OR = 1.2) and current antibiotic medication (OR = 1.5), had a small significant association with candidiasis. Independent predictors for bacterial vaginosis were having multiple sex partners in the past month (OR = 1.6), being unmarried (OR = 1.5), being unemployed (OR = 1.3) being a prostitute (OR = 1.5) and not currently using antibiotic medication (OR = 2.5). The epidemiological profiles were consistent with trichomoniasis and bacterial vaginosis being sexually transmitted diseases with epidemiology different from that of gonorrhoea and chlamydia and different from each other, and candidiasis being a disease in which constitutional factors are more important than issues relating to sexual transmission.