Although a single, 2-gm dose of metronidazole has been approved for the treatment of vaginal trichomoniasis, this regimen has not gained general acceptance. We compared the single, 2-gm dose versus the regimen of 250 mg administered three times daily for seven days. Two hundred sixty-three women with vaginal trichomoniasis were treated. One hundred seventy returned for follow-up. Of them, 96 received the single, 2-gm dose and 74 the seven-day treatment. The cure rates were 93.8% and 97.3%, respectively, and were not significantly different. These data compare favorably with those from previous studies. The side effects were minimal and occurred with greater frequency in the group receiving the single, 2-gm dose; nevertheless, the difference was not significant. We recommend the 2-gm regimen for the treatment of vaginal trichomoniasis because of its easy administration, better patient compliance and lower cost.