The National Research Program 1A on Primary Prevention of Cardiovascular Disease in Switzerland was designed to determine whether community health education can reduce cardiovascular risk factors in whole population groups. Two towns (12,000 inhabitants each) in the French-speaking and two (16,000 inhabitants each) in the German-speaking part of the country were selected for either intervention or comparison. Following baseline screening in 1977 (stratified random samples) and the community intervention program (1978-1980), a final assessment on the initial participants was made at the end of 1980. In intervention towns, 26.2% of the regular smokers quit during this period compared with 18.1% in the reference towns. In addition, a significant net increase in the proportion of hypertensive patients under effective control was observed. A reduction in cholesterol levels was noted in both the intervention and the reference towns, with no difference between them. However, cholesterol levels in a subgroup of women participating in program activities as compared with those not participating were significantly reduced. The program, with extensive involvement of a diversity of community groups, has enjoyed continued support, even after the end of the research experience, thus demonstrating the viability and acceptability of community-oriented preventive action.