Ischaemic heart disease (IHD) in prosperous Western populations rose markedly in the 1940s, peaked between 1970 and 1975 and then fell variably--by about 50% in the USA and Australia. Undoubtedly, decreases in serum cholesterol levels, in the incidence of hypertension and in smoking frequencies are largely responsible. In South Africa, in all population groups other than blacks, IHD rates rose analogously, with Asians and whites attaining very high rates. However, from 1978 to 1989, the total death rate among white males (per 100,000 world population) fell from 1,002 to 631 (37%), and the IHD mortality rate from 312 to 139 (56%). Rates for Asians were 1,306-1,130 (14%) and 355-226 (36%), respectively, and for coloureds 1,691 to 1,392 (18%) and 171 to 110 (36%). For blacks, the total mortality rate remained unchanged; IHD rates were low, but these data are unreliable. Percentage falls in the IHD rate exceed those in the total death rate, especially among whites, indicating true decreases in IHD rate. Understandably, the accuracy of the data, as with such data overseas, is questionable. Local falls are none the less in line with those noted in Western countries. Rates for whites remain very high, and are even higher for Asians. While knowledge of the reasons for the rises and falls in IHD rates remains incomplete, whites have none the less taken some preventive action, although Asians and coloureds apparently little.