There has been a general decline in mortality from ischaemic heart disease (IHD) in Finland since the beginning of the 1970s. An intensified preventive programme was started in the province of North Karelia in 1972. Between 1974 and 1979 the decline in IHD mortality in North Karelian men was steeper than that in the rest of Finland. This favourable trend was associated with a fall in the levels of major coronary disease risk factors. Case-fatality from acute coronary events did not change much during this period. A levelling off in the decline in IHD mortality has been observed in the 1980s first in North Karelia and later in the whole of Finland. These findings from the official mortality statistics were confirmed in North Karelia by the data from the population-based coronary register. This levelling off in the decline in IHD mortality was associated with levelling off in risk-factor reductions in eastern Finland and with little improvement in risk-related behaviours in Finland during the 1980s. The IHD rates are still high and associated with persistent high risk factor levels and particularly with high serum cholesterol and blood pressure levels. Together with IHD mortality, the decline in total mortality also levelled off both in North Karelia and in the rest of Finland during the early 1980s. Compared with other countries, the rates of coronary disease and total mortality in the middle-aged Finnish population, especially among men, are among the highest in the world.(ABSTRACT TRUNCATED AT 250 WORDS)