We conduct a prospective randomized study, the OACIS-LIPID, to determine whether early use of pravastatin can prevent secondary cardiac events in patients with acute myocardial infarction (AMI) and hyperlipidemia (HL). Three hundred and fifty Japanese patients with AMI and mild to moderate HL are randomly assigned to receive or not to receive pravastatin in an open-labeled fashion. The primary dose of pravastatin is 10 mg per day, which is a standard dose for the Japanese population. Both groups receive dietary counseling. Over a 9-month follow-up period, the combination of the endpoints (death, nonfetal myocardial infarction, unstable angina, noncardiac rehospitalization, revascularization and nonfetal stroke) will be evaluated. The results of the OACIS-LIPID study will determine the utility of a practical dose of hydroxymethylglutaryl coenzyme A reductase as an early intervention in AMI.