Abstract: This report describes the discovery of cercarial dermatitis in AU Area, Xizang AU-tonomous Region. It is the first record in a locality more than 4 000m above sea level, The cercaria is temporarily identif ied as Trichobilharzia sp. which is closcly related to T paoi by measurement and general structure. The intermediate host is a fresh water snail, Radix cucunouica. Experimental infection to two human volunteers caused typical lesion of skin. The foci of cercarial dermatitis in Ali Area and nearby countrysides are discussed (Plates 1-3).