We directly compared the safety and efficacy of atorvastatin and simvastatin in hypercholesterolemic patients. This 1-year, randomized, double-blind study was performed at 9 community-and university-based research hospitals in Australia, 177 patients between the ages of 18 and 80 years with baseline low-density-lipoprotein (LDL) cholesterol greater than or equal to 4.14 and less than or equal to 7.76 mmol/L (160 and 300 mg/dl, respectively) and triglycerides less than or equal to 4.52 mmol/L (400 mg/dl) received once daily dosing with atorvastatin 10 mg or simvastatin 10 mg, At week 16, the dose of medication was titrated to atorvastatin 20 mg or simvastatin 20 mg if patients did not meet LDL cholesterol target of less than or equal to 3.36 mmol/L (130 mg/dl), Efficacy was reported as percent change from baseline in LDL cholesterol, total cholesterol, very low density lipoprotein cholesterol, total triglycerides, high-density lipoprotein cholesterol, apolipoproteins A1 and B, and lipoprotein(a). Atorvastatin caused significantly greater reductions from baseline than did simvastatin for LDL cholesterol, total cholesterol, very low density lipoprotein cholesterol, triglycerides, and apolipoprotein B (p < 0.05). No patient in either treatment group had clinically important elevations in creatine phosphokinase, alanine aminotransaminase, or aspartate aminotransaminase. No serious adverse events were considered associated,vith treatment. With atorvastatin 10 mg, 46% of the patients achieved LDL cholesterol target goal by week 16, whereas only 27% of the simvastatin patients achieved the target goal at the 10-mg dose. This cholesterol-lowering profile affords utility in many patient types.