In addition to their high-intensity effects on the reduction in low-density lipoprotein (LDL) levels, rosuvastatin and atorvastatin would be expected to also reduce small dense LDL (sdLDL) levels. To determine which reduces sdLDL levels more, we performed the first meta-analysis and meta-regression of randomized head-to-head trials of rosuvastatin versus atorvastatin therapy. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched through April 2012. Eligible studies were prospective, randomized controlled trials of rosuvastatin versus atorvastatin therapy reporting final sdLDL (directly measured or calculated) levels as an outcome. For each study, data regarding final sdLDL levels in both the rosuvastatin and atorvastatin groups were used to generate mean differences (MD) and 95 % confidence intervals (CI). Meta-regression analysis was performed to determine whether the effects of rosuvastatin therapy were modulated by the prespecified factors. Of 159 potentially relevant articles screened initially, 28 reports of randomized trials enrolling a total of 7802 patients were included. Pooled analysis suggested a significant reduction in final sdLDL levels among patients randomized to rosuvastatin versus atorvastatin therapy (MD, -1.56 mg/dl; 95 % CI, -2.30 to -0.83 mg/dl; P < 0.0001). The meta-regression coefficients were statistically significant for the baseline LDL/sdLDL level and the difference in LDL changes between the two groups. In conclusion, rosuvastatin rather than atorvastatin therapy is likely more effective in reduction of sdLDL levels. It should be further investigated whether the reduction in sdLDL levels implies overt clinical benefits of rosuvastatin over atorvastatin.