Nonspecific bacterial vaginosis, defined as the presence of clue cells, was treated in a randomized, double-blind study with (1) tinidazole 2g as a single dose (82 patients), (2) tinidazole 2 g on 2 consecutive days (84 patients), and (3) with placebo (81 patients). The cure rates, both clue cells and Gardnerella vaginalis absent, were 51, 74 and 4%, respectively. A closer clinical and microbiological evaluation showed the 2-day regimen to be superior.