Magister Chirurgiae Dentium (MChD) / The South African population is made up of Blacks, Whites, Coloureds and Asians. Since each population group is distinct in its culture and habits and have widely differing life styles and socioeconomic levels an ideal oppurtunity exists for the study of environmental influences on the aetiology of particular cancers. In addition accurate epidemiological data is essential in order to assess changing .patterns of the disease and the efficacy of the prevention programmes. The aim of this study was to etermine age standardised incidence rates and age specific morbidity rates of intra-oral squamous cell carcinoma for Blacks on the Witwatersrand. All new cases of intra-oral cancer during the period (1971-1980) were traced. The population at risk was determined from the National Population Censuses of 1970 and 1980. According to the method used in the International Union Against Cancers (U.I.C.C.) publication (Waterhouse et al 1976 and 1982) age standardised incidence rates and age specific morbidity rates were calculated for tongue, floor of mouth, buccal mucosa, hard and soft palates and gingivae and alveolar ridge using standard World, European and African populations. These results indicate that in the population group studied intra-oral cancer is much more common in males and than females (5,55:1 standardised rates) most commonly affects the tongue followed by the floor of mouth, palate, buccal mucosa and gingivae and alveolar ridge and is a disease of the elderly occurring most commonly in the seventh decade in males and in the sixth decade in females. When compared with standardised rates reported, either for Blacks in other geographic locations in South Africa, or for other population groups in this country, or for selected countries elsewhere in the World, important differences have emerged which probably reflect differences in exposure to specific aetiological agents amongst the various population groups compared.