Atorvastatin and rosuvastatin at maximal doses are both highly effective in lowering low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels. Rosuvastatin has been shown to be more effective than atorvastatin in lowering LDL-C, small dense LDL-C and in raising high-density lipoprotein (HDL) and its subclasses. Intestinal lipoproteins containing apolipoprotein (apo) B-48 are also thought to be atherogenic particles. Our purpose in this study was to compare the effects of daily oral doses of atorvastatin 80 mg/day and rosuvastatin 40 mg/day over a 6-week period on serum apo B-48 (a marker of intestinal lipoproteins) and remnant lipoprotein cholesterol (RemL-C) levels (a marker of partially metabolized lipoproteins of both intestinal and liver origin), using novel direct assays in 270 hyperlipidemic men and women. Both atorvastatin and rosuvastatin caused significant (p<0.0001) and similar median decreases in TG (-33.0%, -27.6%), RemL-C (-58.7%, -61.5%), and apoB-48 (-37.5%, -32.1%) as compared to baseline. Our findings utilizing a specific immunoassay and a fairly large number of subjects extend prior studies indicating that statins significantly lower apolipoprotein B containing lipoproteins of both intestinal and liver origin.