A national investigation to determine the prevalence of Huntington''s chorea in South Africa showed that 481 persons have died from or are presently suffering from the disorder. The prevalence rate of 0.1/106 in the South African Negro population is much less than the estimate of 22/106 in the White and Colored groups. The great variation in the ethnic distribution of the disease probably reflects the diverse origins of the different population groups of South Africa.