The National Research Program 1 A on "Primary Prevention of cardiovascular disease in Switzerland' was designed to determine whether community health education can reduce cardiovascular risk factors in the population. Two communities (12,000 inhabitants each) in the French speaking and two (16,000 inhabitants each) in the German speaking part of the country were selected either for 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 performed at the end of 1980. Amongst the regular smokers, 26,2% stopped during this period in the intervention communities whereas 18,1% did so in the reference cities. 4,7% of non-smokers began to smoke during the same period in the intervention communities whereas 7,8% did so in the reference cities. Plasma thiocyanate measurement suggested reliable answers on smoking status. These results suggest that community health education may be effective in preventing harmful health consequence of smoking.