Abstract: Com ptotheca acuminata. Decne is a kind of herbal drug with anti-cancer effect. Camptothecine, had a marked anti-cancer efficacy. Camptotheca acuuiinata tincture made from the fructus of Camptotheca acuminata Decne, DMSO and alcohol was used in topical treatment of 101 psoriatics, the lesions cleared completely in 13 cases, nearly cleared in 29 cases, cleared more thatt 1/2 in 32 cases. There were no obvious systemic side effects and a moderate contact dermatitis was induced in 10 cases. The authors used two kinds of animal experimental models, mouse vaginal epithelium in estrus cycle and mouse tail scale epidermis, to study the therapeutic mechanism of the tincture. Results of the experiments suggested that topical application of Camptotheca acuminata tincture could, on the one hand, suppress the mitosis of psoriatic epidermis and, on the other, promote the formation of a granular layer, thus correcting the pathologic process of hyperplasia and parakeratosis in the psoriatic epidermis.