Blacks treated in Sacramento County (CA) Clinics were most likely to have gonorrhea. Chicanos were slightly more likely to have nonspecific urethritis and other sexually transmitted diseases, and Whites were most likely to be uninfected. Whites tended to name greater numbers of different sexual partners, but differences among the three groups were not statistically significant. Black men more frequently reported to clinics with genitourinary symptoms and delayed significantly longer before seeking treatment. Future research should assess the relative contributions of sexual and health behaviors to the distributions of different sexually transmitted diseases in different groups.