A recent study on population health in two Swiss cantons (Jura and Neuchatel) makes it possible to determine the relative importance of various problems and to set priorities in preventive activities. Attention is focused on traffic accidents (first cause of death among children and young adults up to 25 years) and their link with alcohol consumption, on suicide (first cause of death among adults 26-40 years old), on lung and breast cancer. For general practitioners, essential preventive activities appear as follows: screening of depression and risk of suicide, of alcohol and tobacco addiction; counselling on addictions (brief intervention); recommending mammography to all women above 50.