In Japan the age-adjusted death rate from cerebrovascular diseases has decreased for both males and females since 1965. This downward trend accelerated in 1971. This is not due to artifacts such as changes in diagnostic methods of stroke and in rules for coding cause of death on death certificates. The progress and spread of detection, treatment and control of hypertension appears to have been the greatest contributing factor. Furthermore, improvement in the dietary habits, that is, a decrease in salt intake and an appropriate increase in the amount of animal fat and protein taken are also considered to have contributed to the decline in stroke mortality. The regional difference in the standardized mortality ratio for stroke markedly observed in 1960 was still seen even in the 1970's, but the difference became smaller. Mechanization of farming works may be partly accountable for the decrease in the regional difference.