Two randomized multifactorial primary preventive trials (Oslo, MRFIT) are conducted among high-risk subjects with personalized intervention. Multifactorial risk is reduced in both trials, but serum cholesterol differs among groups only in Oslo where the incidence of severe cases is significantly lowered. The WHO cooperative trial allocates at random groups of subjects with a mainly collective intervention. Among the 4 national projects, incidence or mortality are only reduced when multifactorial risk and serum cholesterol are reduced. A community programme has been conducted during 10 years in North Karelia where the risk factor levels and mortality have decreased more than in the next reference area. The whole of the results is rather consistent: a quantitative relationship is put forward between the reduction of multifactorial risk and the frequency of the disease when a certain reduction of serum cholesterol is obtained. Prevention is now a public health problem.