Patients with elevated low-density lipoprotein (LDL) cholesteral levels are at high risk of cardiovascular events but are often undertreated and fail to achieve lipid goals. This open-label, noncomparative, multicenter study assessed efficacy and safety of rosuvastatin 40 mg for ≤96 weeks in 1,380 patients with severe hypercholesterolemia, including heterozygous familial hypercholesterolemia. Patients ≥18 years old with fasting LDL cholesterol ≥190 and ≤260 mg/dl and triglycerides <400 mg/dl entered a 6-week dietary lead-in, before receiving rosuvastatin 40 mg for 48 weeks. An optional additional 48-week treatment period followed. The initial period had 2 primary end points: percentage of patients achieving National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III LDL cholesterol goals at 12 weeks, and long-term safety, assessed during 48 weeks by incidence and severity of adverse events (AEs) and abnormal laboratory values. Safety was the primary end point in the extension period. At 12 weeks, 83% of patients achieved NCEP ATP III LDL cholesterol goals, which were maintained during 48 and 96 weeks (81% and 84%, respectively). At 48 weeks, rosuvastatin 40 mg reduced LDL cholesterol from baseline by 52% and increased high-density lipoprotein (HDL) cholesterol by 11% (both p <0.0001). At 96 weeks, LDL cholesterol was reduced by 54% and HDL cholesterol increased by 13%. Rosuvastatin 40 mg was well tolerated during 96 weeks. The overall pattern and incidence of AEs and abnormal laboratory values were consistent with the published safety profile of rosuvastatin and higher doses of other statins. In conclusion, long-term treatment with rosuvastatin 40 mg is safe and effective in patients with severe hypercholesterolemia.