The author reviews the literature since 1939 on carcinogenesis in hamsters. He analyzes Syrian hamster response to chemical carcinogens in comparison to the responses of other species, stressing interesting facets of the response of the hamster. It is his hypothesis that most contradictory observations made in the study of chemical carcinogenesis in random‐bred hamsters may be explained by genetic differences and that the study of this response in inbred pedigreed hamster lines will yield much information. The author believes that some correlation to the response of man to chemical carcinogens might be defined from such studies.