Sexual differences of Carrion Corvus corone orientalis and Jungle crows C. macrorhynchos japonensis were examined. Crows were captured by 'multi-trap' during April 1989 to June 1990 in Ikeda, eastern Hokkaido. Body mass, bill length, natural wing length, tail length, and tarsus length of carcasses were all measured. They were aged by tongue-markings and dissected in order to examine their reproductive organs. They were classified into two age-classes (adults and juveniles). Males were larger than females in all measurements for adults and juveniles of both species. Discriminant function analysis was carried out. The probability of correct discrimination of sexes for Carrion Crows was 87% for adults and 80% for juveniles. For Jungle Crows it was 91% for adults and 92% for juveniles. The sexes of both adult and juvenile Jungle Crows could be determined by discriminant function analysis.