Koro endemic among school children in Guangdong, China

The occurrence of a koro endemic among elementary-school children is reported, the nature of the occurrence is elaborated, and the possible cause for the endemic is discussed. The episode occurred within a period of three days in Fuhu village in Guangdong Province in southern China in late May 2004. It involved 64 male students. Familiarity with koro in the community, tension among schoolchildren due to their studies, and a misleading warning and instruction from the school principle are considered contributing factors in the occurrence of this mass-hysterialike, unique phenomenon.