A prescription-event monitoring (PEM) study has confirmed that fluconazole, a bis-triazole oral antifungal drug, is a safe and effective treatment for vaginal candidiasis. Useful information was available on 15,015 questionnaires returned by general practitioners. The events were compared with those recorded in PEM studies of itraconazole and 31 other drugs in a total of more than 330,000 patients. The frequency of events in the study of itraconazole was almost identical. Upper respiratory tract and genito-urinary infections were reported with above-average frequency but the relationship was with the disease being treated rather than the drug itself. No serious adverse effects were recorded with an unacceptably high incidence. None of the 125 deaths was caused by fluconazole. Although contraindicated for vaginal candidiasis in pregnancy, fluconazole was taken by 289 women at some time during the months before or during pregnancy; a follow-up study by questionnaire of the outcome of pregnancy showed fluconazole to be without harmful effect. It is concluded that fluconazole is a well tolerated drug in the treatment of vaginal candidiasis and is associated with very few adverse effects.