Koro epidemics, characterized by panic due to fear of genital retraction, involving more than 2000 victims, mainly young men, occurred in Hainan Island and Leizhou Peninsula of Guangdong Province, China, in 1984–85 and 1987. A questionnaire survey of 214 victims of these epidemics was conducted in 1988. The survey focused on symptom manifestation, personality profile, life problems, and folk belief. The results of the “koro” group were compared with those of a “clinic” group with minor psychiatric disorder and a “control” group from the non-clinical, non-koro episode population in the epidemic area. The results revealed that the victims of the koro epidemics were characterized by low intellectual endowment and strong acceptance of koro-related folk beliefs. The results support the hypotheses that: a) a koro attack is a psychologically induced anxiety-panic condition; b) the presence of an intensive belief in the culturally related concept of koro makes the subject vulnerable to the attack; and c) social crisis or tension serves as a trigger for the occurrence of the epidemic.