In order to study the incidence of ischaemic heart disease and arterial hypertension among different groups of population in the Yakut Republic and the peculiarities of their course among the indigenous inhabitants of the city of Yakutsk and of rural areas of the Yakut Republic, and among migrants, living in the Yakut Republic for at least 10 years, 1003 males, aged 50-59 years, were examined. The clinical course of ischaemic heart disease and arterial hypertension was also studied in the 2 mentioned groups of population treated in internal medicine clinics, and the data of 650 autopsies were examined. The epidemiological study was conducted in strict conformity with the WHO program.