The objective of this multicenter, randomized, open-label, parallel-group, 8-week study was to evaluate the comparative dose efficacy of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor atorvastatin 10, 20, 40, and 80 mg compared with simvastatin 10, 20, and 40 mg, pravastatin 10, 20, and 40 mg, lovastatin 20, 40, and 80 mg, and fluvastatin 20 and 40 mg. Investigators enrolled 534 hypercholesterolemic patients (low-density lipoprotein [LDL] cholesterol > or = 160 mg/dl [4.2 mmol/L] and triglycerides < or = 400 mg/dl [4.5 mmol/L]). The efficacy end points were mean percent change in plasma LDL cholesterol (primary), total cholesterol, triglycerides, and high-density lipoprotein cholesterol concentrations from baseline to the end of treatment (week 8). Atorvastatin 10, 20, and 40 mg produced greater (p < or = 0.01) reductions in LDL cholesterol, -38%, -46%, and -51%, respectively, than the milligram equivalent doses of simvastatin, pravastatin, lovastatin, and fluvastatin. Atorvastatin 10 mg produced LDL cholesterol reductions comparable to or greater than (p < or = 0.02) simvastatin 10, 20, and 40 mg, pravastatin 10, 20, and 40 mg, lovastatin 20 and 40 mg, and fluvastatin 20 and 40 mg. Atorvastatin 10, 20, and 40 mg produced greater (p < or = 0.01) reductions in total cholesterol than the milligram equivalent doses of simvastatin, pravastatin, lovastatin, and fluvastatin. All reductase inhibitors studied had similar tolerability. There were no incidences of persistent elevations in serum transaminases or myositis.