12,064 survivors of myocardial infarction have been randomised in a 2x2 factorial design to more intensive versus standard cholesterol-lowering treatment, using 80 mg or 20 mg daily simvastatin, and separately to homocysteine-lowering with folic acid plus vitamin B12 or matching placebo. Follow-up will continue until there are at least 2800 confirmed major vascular events (MVE), defined as non-fatal myocardial infarction, coronary death, stroke or arterial revascularisation. The primary outcome is the incidence of first MVE during the scheduled treatment period.