The Di.S.Co. Project--Sezze District Community Control--is aimed at achieving in the general population the prevention of chronic diseases through community intervention. Two areas are enrolled, one for intervention (25,706 subjects) and one for reference (12,655 subjects). In 1983 the first survey was conducted on a sample of males and females aged 20-69, and some risk factors for cardiovascular diseases were measured. In 1986 a second screening was conducted on the same sample examined in 1983 and in a new one to evaluate the effect of community treatment during the three-year intervention. The main net differences obtained in the treatment area against controls (by the paired analysis), adjusted by the initial levels of the risk factors considered, were: in males body mass index: -1.3% and number of cigarettes smoked per day: -5.1%; in females systolic blood pressure: -2.1%, body mass index: -3.2% and number of cigarettes smoked per day: -34.4%. The theoretical probability of death from atherosclerotic cardiovascular diseases in 25 years was estimated by the multiple logistic function and in three years it increased by 1% in males, while for females it decreased by 6.5%.