To monitor recent changes in Japan in diet and risk factors for cardiovascular disease (CVD), in the light of the decline on coronary heart disease, total serum cholesterol levels and other risk factors were compared between two nationwide health surveys in 1980 and 1989 conducted in the same population as the annual National Nutrition Surveys. Between 1980 and 1989, age-adjusted total serum cholesterol levels increased from 4.84 to 5.22 for men and from 4.91 to 5.24 mmol/l for women. Prevalence of age-adjusted hypercholesterolaemia of > or = 5.68 mmol/l (220 mg/dl) increased from 15.8% to 29.4% for men and from 18.4% to 30.6% for women. Decline in blood pressure was observed for both sexes. Prevalence of smoking decreased from 64.7% to 58.7% in men while prevalence in women remained low (from 10.1 to 9.9%). Considerable increases in total serum cholesterol levels do not offer an explanation of the recent decline in mortality from coronary heart disease in Japan. This may, in part, be related to a decline in blood pressure levels.