In Switzerland the age-standardised death rate for 'all diseases of the circulatory system' decreased by 22% in males and by 43% in females between 1951 and 1976, which represented a third and nearly a half respectively of the decrease in all deaths. Mortality was reduced by 13% in males and by 40% in females for non-rheumatic heart disease and hypertension, and by 36% and 47% respectively for cerebrovascular disease. These reductions were on the whole greater than those observed in the 13 other developed countries studied. From 1951 to 1976 consumption of animal fats per caput increased by 20% in Switzerland, in spite of a 46% reduction in milk intake. Throughout the same period, smoking increased among women while it remained steady or possibly declined in men. During the last decade a threefold rise in the sales of antihypertensive drugs was observed. Oral contraceptives seem to have been widely used by Swiss women since the 1960s. There were also increases in the proportion of women in professional occupations, and in urbanisation. The advent of the economic recession was associated with a sudden rise in mortality from non-rheumatic heart disease and hypertension in 1974-76.