Although therapy with statins has been shown to lower LDL-cholesterol levels effectively and, consequently, vascular morbidity and mortality, evidence for the long-term efficacy and safety of such treatment is limited. Researchers in the Heart Protection Study Collaborative Group randomly allocated 20,536 patients at high risk of vascular and nonvascular outcomes to either 40 mg simvastatin daily or placebo. In-trial follow-up was 5.3 years and post-trial follow-up (when statin therapy was similar in both groups) extended the duration to 11 years. During the in-trial period, simvastatin was associated with an average lowering of LDL-cholesterol levels by 1.0 mmol/l and a reduction in major vascular events by 23% compared with placebo. Over the 11-year follow-up, no significant differences in the incidence of cancer or mortality were observed between the two groups.