In a clinical study from October 1985 to July 1987, we tested the efficacy of 3 different imidazole compounds in 112 male patients suffering from pityriasis versicolor. The diagnosis was made according to clinical criteria and confirmed by microscopical investigation. Our results prove the necessity of daily treatment over a period of at least 2 weeks. After 2 weeks, the microscopical examination should be repeated. Sprays and shampoos seemed equally effective. The relapse rate turned out to be rather high. The symptom-free interval between therapy and relapse could not be correlated to any of the forms of treatment. Those patients who had to be treated for more than 2 weeks were most likely to develop a relapse within a shorter period.