In this study, the risk profiles and epidemiologic interrelationships of 13 sexually transmitted diseases (STD) were studied in 12,170 men and 6,125 women attending the Adelaide STD Clinic in South Australia from 1988 to 1991. Fifteen independent variables for men and 19 independent variables for women were analyzed by multiple logistic regression. Risk profiles were depicted graphically from the odds ratios of independent associations with the factors studied. These profiles showed a marked influence of socioeconomic factors on the epidemiology of hepatitis B infection, syphilis, scabies (in contrast with the pattern for pediculosis pubis), gonorrhea, and trichomoniasis. The risk profiles for warts, herpes, and molluscum contagiosum are similar and contrast with those of gonorrhea and chlamydia. The vaginitides showed clear differences, with bacterial vaginosis being directly associated with and candidiasis inversely associated with variables relating to sexual activity. In women, gonorrhea was a strong predictor of chlamydial infection and women with gonorrhea had twice the rate of other STDs collectively, compared with women who did not have gonorrhea. However, most other associations between individual STDs and other STDs collectively were of an inverse nature, although several strong associations between individual STDs were found on univariate analysis.