The purpose of this study was to examine the efficacy and safety of ezetimibe (EZE) coadministered with simvastatin (SIMVA) in a large cohort of African Americans with primary hypercholesterolemia. In a multicenter, randomized, double-blind study, patients were considered eligible for enrollment if after a washout/placebo run-in period, low-density-lipoprotein (LDL) cholesterol level was > or = 145 and < or = 250 mg/dl and triglyceride level was < or = 350 mg/dl. Eligible patients were randomized to SIMVA 20 mg coadministered with either EZE 10 mg (n = 124) or placebo (n = 123) for 12 weeks. At study endpoint, EZE/SIMVA 10/20 mg resulted in a significant mean percent reduction in LDL cholesterol from baseline of 45.6% compared with 28.3% for SIMVA 20 mg alone (p < or = 0.01). There were significantly greater mean reductions in total cholesterol (33% vs. 21%), triglycerides (median 22% vs. 15%), nonhigh-density-lipoprotein (non-HDL) cholesterol (42% vs. 26%), and apolipoprotein B (38% vs. 25%) with EZE/SIMVA 10/20 mg compared with SIMVA 20 mg alone, respectively (p < or = 0.01). There was no difference in HDL cholesterol between the EZE/SIMVA 10/20-mg and SIMVA 20-mg alone groups (+1% vs. +2%, respectively). Coadministration of EZE/SIMVA 10/20 mg demonstrated a safety profile similar to that of SIMVA 20 mg. In conclusion, EZE/SIMVA 10/20 mg provided significantly greater improvement in atherogenic lipid profiles and was well tolerated compared with SIMVA 20-mg monotherapy in a large cohort of African Americans with primary hypercholesterolemia.