OBJECTIVES: To compare the effectiveness of statins in a real world setting as measured by percentage low density lipoprotein cholesterol (LDL-C) reduction and percentage total cholesterol (TC) reduction in patients newly initiated on statin therapy. METHODS: For this retrospective cohort study, patients newly initiated on common start doses of statin therapies (rosuvastatin 10 mg, simvastatin 10/20 mg, pravastatin 20/40 mg and atorvastatin 10/20 mg) between January 1, 2003 and August 31, 2005 were identified from the UK DIN-LINK database. Patients with no dyslipidemic therapy in the 12 months preceding their initial statin prescription and an LDL-C or TC measurement less than 6 months before and at least 1 month after initiating statin therapy were included in the study. Adjusted percent LDL-C reductions and percent TC reductions were compared using linear regression techniques. RESULTS: A total of 2151 patients with complete LDL-C data were identified. Rosuvastatin (n=159), atorvastatin (n=836), simvastatin (n=1107) and pravastatin (n=49) groups were similar with respect to mean age (64.5, 64.4, 65.1 and 65.1 years respectively) and baseline LDL-C levels (4.4, 4.3, 4.3 and 4.0 mmol/L respectively). After adjusting for age, gender, baseline LDL-C, therapy duration and 2003 European guideline risk factors, patients initiated on rosuvastatin achieved a significantly greater percentage LDL-C reduction (44.8%; 95% confidence interval 42.1%-47.4%) than patients initiated on atorvastatin (40.4%; 39.2%-41.5%), simvastatin (36.5%; 35.5%-37.5%) or pravastatin (29.9%; 25.1%-34.5%): all p<0.01. Similarly, in patients where complete TC data was available (n=7070), patients initiated on rosuvastatin (n=475) had a significantly greater adjusted percentage TC reduction (31.3%; 30.1%-32.5%) than patients initiated on atorvastatin (n=2662; 28.2%; 27.7%-28.7%), simvastatin (n=3665; 25.3%; 24.9%-25.7%) or pravastatin (n=268; 20.7%; 19.1%-22.3%): all p<0.0001. CONCLUSIONS: In patients newly initiated on usual start doses of statins in routine practice, rosuvastatin was more effective in lowering both LDL-C and TC than atorvastatin, simvastatin and pravastatin.