One hundred male sexual partners of women with anaerobic vaginosis (AV) were screened for the presence of sexually transmitted diseases (STD). Thirty male partners had evidence of non-gonococcal urethritis (NGU), compared to 5 in the control group (P less than 0.05). Chlamydia trachomatis was isolated from 14 male partners, compared to 3 in the control group. Forty-five male partners required treatment for STDs, compared to 11 in the control group (P less than 0.02). Nine (40%) male partners with chlamydia-negative NGU were successfully treated with metronidazole alone while 10 required Deteclo in addition. There was no significant association between Bacteroides ureolyticus and chlamydia-negative NGU. Screening of male partners resulted in the treatment of STDs in 62 additional patients who would have otherwise not received treatment. The results suggest that examination of male partners of women with AV results in an increased yield of STD diagnoses.