Previously, sex differences among the various tooth types in Japanese skulls were examined to facilitate choosing an implant diameter similar to the cervical diameter of each tooth, and it was found that mesiodistal diameters at the cementoenamel junction were narrower in women than in men. Also interesting and relevant to the selection of implant diameter is the possible existence of racial differences in diameters at the cementoenamel junction. The purpose of this research was to test the hypothesis that the diameter at the cementoenamel junction of the tooth differs in humans of different races. We compared 106 skulls of unknown sex collected from South Asia with the skulls of Japanese women. Our conclusions are as follows: (1) Except for the lower canine, no significant racial differences were found in the labiolingual diameter of any teeth. (2) Except for the upper canine, upper central incisor, lower second premolar, and lower first premolar, a significant racial difference was found in the mesiodistal diameter. In all teeth in which this value differed, the mesiodistal diameters of South Asians were narrower than those of Japanese women, except for the lower canine. (3) The labiolingual and mesiodistal diameters of the lower canine were significantly larger in South Asians than in Japanese women. (4) Among South Asians, no significant left/right differences were found in the diameter at the cementoenamel junction of any tooth.