The therapeutic efficacy of Cassia alata leaf extract against Pityriasis versicolor has been reported for the first time involving humans. For the collection of clinically effective antifungal compounds from the leaves of Cassia alata, a simple procedure has been devised. A 10-year human study indicates that the leaf extract can be reliably used as a herbal medicine to treat Pityriasis versicolor. The leaf extract has no side-effects.