HMG Co-A reductase inhibitor (statin) treatment for primary prevention of coronary heart disease (CHD) can be justified on risk-benefit grounds when the CHD event rate is as low as 0.6% per year, and treatment policies will therefore be influenced by cost-benefit considerations. We examined the likely impact for the Scottish population of different policies, targeting statin treatment for primary prevention at CHD event risks of 3.0%/year (SMAC guidelines); 2.0%/year (European Joint Task Force guidelines); 1.5%/year (WOSCOPS study); and 0.6%/year (AF/TexCAPS study). CHD risk was calculated by the Framingham function. We also examined the impact of targeting people with any cholesterol concentration, and those with cholesterol ≥5.0 mmol/l (table). Percentages of Scottish men and women age 35-64 with 95% confidence intervals Policy TC* ≥ 5mmol/l TC < 5mmol/l Any TC Secondary prevention 7.8 (6.9-4.6) 0.8 (0.5-1.0) 8.5 (7.7-9.4) Primary prevention at CHD risk 3.0% per year 1.7 (1.3-2.1) 0.1 (0.0-0.1) 1.7 (1.3-2.1) Primary prevention at or CHD risk 2.0% per year 5.8 (5.1-6.5) 0.5 (0.3-0.7) 6.3 (5.6-7.1) Primary prevention at or CHD risk 1.5% per year 10.4 (9.5-11.4) 1.0 (0.7-1.3) 11.4 (10.5-12.4) Primary prevention at or CHD risk 0.6% per year 35.5 (34.0-37.0) 4.5 (3.8-5.1) 40.0 (38.4-41.5) Primary prevention at or lifetime† 2.0% per year 13.4 (12.3-14.5) 1.1 (0.8-1.5) 14.5 (13.4-15.6) * TC - Total cholesterol concentration; † - Age projected to 60years if current age <60years There is a large increase in the percentage of the population for statin treatment as the target CHD risk is lowered. Over one third of the population would be candidates for treatment at the AF/TexCAPS level of CHD risk. Targeting at lifetime risk as recommended in European Joint Task Force guidelines at CHD risk 2%/year more than doubles the target population for primary prevention at the same risk. At higher CHD risk, lowering cholesterol concentration to <5 mmol/l in the target population matters little. However this percentage increases at lower CHD risk.