The role of cholesterol and phosphatidylcholine on hepatic very low density lipoprotein secretion was investigated with rat hepatocytes. Hepatic very low density lipoprotein secretion (apo B, apo E, cholesterol, triglyceride, phosphatidylcholine) was decreased by the reduction of hepatic phosphatidylcholine content. However, cholesterol loading into hepatocytes did not affect hepatic very low density lipoprotein secretion. Hepatic apolipoprotein contents were constant and were not influenced by a change of hepatic cholesterol and phosphatidylcholine contents. These results suggest that lipids, which are constituents of lipoproteins, play different roles on hepatic very low density lipoprotein secretion.