Joint European Task Force Guidelines suggest targeting lipid-lowering treatment at a CHD risk of 20% over 10 years, but also suggest projecting a targeted person's age to 60 years if their actual age is less than 60 years Other guidelines (Standing Medical Advisory Committee, Joint British Guidelines) also suggest targeting at CHD risk, but advise using current age rather than projected age. We examined the likely impact for the Scottish population of targeting statin treatment for primary prevention at a CHD risk of 20% over 10 years, and serum total cholesterol concentration ≥5.0 mmol/l using projected age' and actual age. Data on risk factors was obtained from 3963 people aged 35-64 for primary prevention from the 1995 Scottish Health Survey. CHD risk was calculated by the Framingham function. Men Women Age (years) PR* AR† PR AR 35-44 21.4 0.3 1 1 0 1 45-54 24 7 1.0 3.2 1 0 55-64 26.9 7.6 4.7 3 9 Total 35-64 24 1 10.1 2.9 1.6 95%CI 22.1-26.1 8.7-11.4 2.2-3.6 1.1-2.1 * PR - projected risk ie CHD risk 20%/10 years caluated with age projected to 60 if current age <60 years † AR - actual risk ie CHD risk 20%/10 years calculated using current age Targeting treatment at projected risk will increase treatment in young people massively. 22% of men in their 30's will be on statins if age is projected to 60, as opposed to no-one if actual age is used. In all men and women aged 35-64, statin use would more than double from 5.4% to 12.4%. The average CHD risk of people aged 35-39 with cholesterol ≥5.0 mmol/l is only 2.4% over 10 years (3.9% for men and 0.8% for women), a level of risk at which benefit from statin therapy has not yet shown to be effective. At this level of risk, 250 people would need treatment for 5 years to prevent one event at a cost of £694,000 per event prevented.