The exact role of the heparin-releasable hepatic endothelial lipase has remained controversial. It has been suggested that it acts in concert with lipoprotein lipase in the step-wise delipidation of triglyceride-rich lipoproteins. On the other hand, there is evidence indicating that high density lipoprotein2 is the preferred substrate for hepatic lipase. Here, it is shown that a moderate (27%) suppression of hepatic lipase activity by estrogen did not impair removal of 3H-labeled very low density lipoproteins (VLDL) triglycerides, suggesting that this enzyme is not a major regulator of VLDL catabolism under physiological circumstances.