Long-term safety and tolerability of ezetimibe plus atorvastatin (EZE + ATV) coadministration therapy were compared to those of ATV monotherapy in patients with primary hypercholesterolaemia. Upon completion of a 12 week randomised, double-blind, placebo-controlled study comparing EZE 10 mg; ATV 10, 20, 40 or 80 mg; EZE + ATV 10, 20, 40 or 80 mg or placebo, 246 patients were enrolled in a 12-month extension, with reassignment to double-blind EZE 10 mg (n = 201) or matching placebo (n = 45) coadministered daily with open-label ATV 10 mg. At intervals of 6 weeks, patients not at National Cholesterol Education Program Adult Treatment Panel II LDL-C goals were titrated to the next higher ATV dose. Safety evaluations included adverse event (AE) reports and laboratory test results. EZE + ATV and ATV monotherapy groups were similar with regard to incidence of all AEs (71 vs. 67%), treatment-related AEs (22 vs. 27%) and discontinuations due to AEs (9 vs. 7%) or treatment-related AEs (6 vs. 7%), respectively. Neither clinically significant elevations in hepatic transaminases or creatine kinase nor any cases of myopathy or rhabdomyolysis were observed in either group during the extension study. After 6 weeks, EZE + ATV 10mg produced greater reductions in low-density lipoprotein cholesterol (LDL-C; -53 vs. -37%), total cholesterol (TC; -38.8 vs. -26.0%) and triglycerides (TG; -28 vs. -12%) and similar increases in high-density lipoprotein cholesterol (4.6 vs. 4.5%) compared to ATV 10 mg, respectively, and these changes were maintained and significant at 1 year (p < 0.01 for LDL-C, TC and TG). More EZE + ATV patients achieved LDL-C goal than ATV patients at study endpoint (91 vs. 78%, respectively; p = 0.02). Thus, the coadministration of EZE + ATV for 12 months was well tolerated and more efficacious than ATV monotherapy.