To investigate the frequency of Shiga toxin-producing Escherichia coli (STEC) infected calves at a breeding farm and cattle at a slaughterhouse in Tohoku area of Japan, the polymerase chain reaction (PCR) was used for detection of genes for Shiga toxin(s). The fecal samples from a total of 204 calves and 306 cattle were examined. The prevalence rates in calves less than 2 months of age, cattle 2-8 months of age, and adults greater than 1 year of age were 39.4, 78.9, and 40.8%, respectively. Detection frequency of STEC in the fecal specimens from calves aged 0-8 months was not different among the breeds of cattle (Holstein: H, Japanese black cattle: B, and F1: HxB). On the other hand, for calves over 12 months of age, the frequency of STEC in Japanese black cattle and F1 were significantly higher than in Holstein cattle. Serogroups of STEC usually identified in human cases of food poisoning (O157, O26, and O111) were not frequently found in the feces of the cattle.