Although it is a common disease entity worldwide, idiopathic carpal tunnel syndrome is rarely seen in black South Africans. This study compares anatomic dimensions of the carpal canal in black and white population groups, using computed tomography. No significant anatomic differences were found between the groups tested; thus, other explanations need to be sought to explain the difference in occurrence of carpal tunnel syndrome in these groups. A parameter, the carpal canal index, was defined and may prove useful in future investigations of this region.