A community-based education program was conducted for persons found to be hypercholesterolemic by screening during cardiovascular surveys, in an urban population, to evaluate the feasibility and effect of the program in primary prevention of coronary heart disease. The subjects were men and women aged 40-64 living in the suburbs of Osaka whose serum total cholesterol was between 240 and 299 mg/dl in both the 1988 and the 1989 surveys. Persons with hypothyroidism, those taking medication for hypercholesterolemia or hypertension, and with a history of stroke and coronary heart disease were excluded. Of the 111 persons who were eligible, 104 persons were recruited for the program on March, 1989. The 104 persons were randomly assigned to either an intensive education group (n = 51) or a usual education group (n = 53). For the intensive education group, seven education classes were held from April to November, 1989. Lectures, practice sessions, interviews, and spot cholesterol measurements were conducted in a local community center. The usual education group received a letter with results from the 1989 survey and dietary instruction in April 1989 and an education class in September 1989. Mean serum cholesterol in the intensive education group showed a 10.0 mg/dl greater reduction in September 1989 and a 9.0 mg/dl greater reduction in March 1990 than in the usual education group (p less than 0.05) while mean HDL-cholesterol did not change in either groups. The intensive education group reported a larger decrease in the dietary frequency of chicken egg, poultry skin and small fishes, foods which are rich in saturated fat and cholesterol. The frequency of fatty meat, butter and fish eggs was low in both groups and did not differ between the two groups after the one-year program. These results indicate that a population-based education program is feasible and effective in reducing serum total cholesterol of hypercholesterolemic persons.