Introduction Many attempts are being made to investigate the precise role of tobacco in the occurrence of cancer of the human mouth, throat, and lungs. This work has been stimulated by recent experimental studies and epidemiological data,1-4 the latter pointing to some significant etiological association between tobacco and these cancers. Such an association also has been demonstrated between mouth and throat cancer, the excessive consumption of alcohol, and certain states of chronic malnutrition, such as the Plummer-Vinson syndrome.5-7 However, tobacco maintains the most consistent association with mouth cancer, as compared with alcohol and diet. Since cigarettes are by far the most widely used form of tobacco in this country, we became interested in studying the effects of cigarette smoke tar in experimental animals. Materials and Methods We have selected as our experimental tissue the oral pouch of the golden hamster (Mesocricetus auratus) because of its proximity to the