The relationship between vaginal pH, microflora, and yeast infection was investigated in 93 women randomly treated with either nystatin or miconazole pessaries and cream for two weeks. The vaginal pH was measured in a control group of 48 women. In the study group, 37 patients defaulted, 39 were cured, and 17 required treatment during the six-month follow-up period. In both study and control groups before and after treatment the mean vaginal pH was in the range of 4.3-4.6. Lactobacilli were plentiful in 78 (91%) out of 86 patients and shows that lactobacilli and yeasts commonly coexist. The influence of other organisms appeared to be negligible. The trial showed that nystatin and micromazole were equallly effective in the treatment of vaginal yeast infection and that the broad-spectrum activity of micronazole offered no advantage in this condition.