One of the 2 controlled preventive trials within the Oslo Study was a non-drug trial on the effect of diet and smoking intervention on coronary heart disease in 1232 middleaged, normotensive, healthy men. All had elevated serum cholesterol and 4 out of 5 smoked every day. The participants in the intervention group met every 6 months during the 5-year study for clinical examination and for dietary and smoking counselling. The effect on serum cholesterol was a 13% lowering (i.e. 10% net reduction compared with control group), and about a 50% reduction in cigarette consumption. The effect on coronary heart disease (fatal and non-fatal myocardial infarction or sudden death) was a 47% lowering of the 5-year incidence in the intervention group compared with the control group (p = 0.02, 2-sided). The main intervention strategies were: information about the risk factor concept to participant and spouse (in groups) individual diet and anti-smoking counselling after finishing an extensive clinical and electrocardiographic examination, including exercise-ECG basis and background for the counselling strategy: the total situation of the participant. Some of the most important items: personality, motivation, diet history, bodyweight, blood lipids and blood sugar anti-smoking advice given individually to all smokers in the intervention group advice that smoking cessation was expected to be of special importance for those with elevated blood lipids.