OBJECTIVE: To compare effectiveness of rosuvastatin to atorvastatin on lipid levels (LDL-C, HDL-C, triglycerides, total cholesterol) and LDL-C goal attainment. METHODS: Patients newly-initiated on rosuvastatin or atorvastatin between August 1, 2003 and June 30, 2004 were identified from a West Coast health plan's claims data for this retrospective, longitudinal cohort study. Patients were excluded if they had any dyslipidemic therapy 12-months preceding their initial statin fill. Propensity score matching on baseline characteristics was used to minimize selection bias between groups. Administrative claims and medical records were utilized to assign patients NCEP risk status and corresponding LDL-C goal. Percent changes in lipid values were computed by comparing pre/post-initiation levels. Adjusted LDL-C change and goal attainment were evaluated using OLS and logistic regression techniques, respectively. RESULTS: A total of 453 patients (217 rosuvastatin/236 atorvastatin) were identified. Mean dose and therapy duration for rosuvastatin were 11mg and 61 days compared to 15mg and 79 days for atorvastatin. Patients receiving rosuvastatin compared to atorvastatin had significantly greater mean percent reductions in LDL-C (35% vs. 26%), total cholesterol (26% vs. 20%), and non HDL-C (33% vs. 25%); all p<0.05. After adjusting for age, gender, baseline LDL-C, NCEP risk status, and therapy duration, reductions in percent LDL-C continued to be statistically significant. No statistically significant differences were found in HDL-C and triglycerides between groups. Percentages of patients achieving their LDL-C goal with rosuvastatin and atorvastatin were 74% and 65%, respectively. After adjusting for baseline differences between groups, significantly (p<0.05) more patients were observed to achieve their LDL-C goal with rosuvastatin (OR=1.87, 95% CI: 1.10-3.17). CONCLUSION: Rosuvastatin was associated with statistically significant reductions in LDL-C, non HDL-C, and total cholesterol compared to atorvastatin. Furthermore, rosuvastatin patients were nearly twice as likely to attain their LDL-C goal compared with atorvastatin when adjusted for baseline differences between groups.