Serum samples from humans in Chongju City, Korea, were tested for the presence of Clostridium perfringens enterotoxin antibody by enzyme linked immunosorbent assay (ELISA). About half of the 1054 samples tested had high ELISA readings, which could be the result of exposure to enterotoxin produced by C. perfringens. The high prevalence of the antibody among the Korean population suggests that foodborne illnesses caused by C. perfringens may be common in Korea even though the occurrence has not been monitored.