The aim of the present study was to determine the effects of exercise on the regulatory in activity of hepatic low density lipoprotein receptor (LDL-R) in experimental hypercholesterolemic (HC) rats. Using a specific assay for the binding of 1 2 5 I-LDL receptor to homogenate, the activities of hepatic LDL-R were measured. It was observed the activity of LDL-R in HC decreased 37% compared with the normal control (NC) rats. HC rats also had a higher level of serum total cholesterol (TC), LDL-Cholesterol (LDL-C) and apolipoprotein B (Apo B). After fed on high-cholesterol diet combined with exercise in swimming for 12 weeks (HE), the exercise rats showed the lowering in level of TC, LDL-C and Apo B compared with HC, and had a higher hepatic LDL-R activity with 26% than that of HC rats. These finding suggested: (1) LDL-R activity was regulated downward in cholesterol-loaded rats; (2) The long-term exercise might be a feedback effect on the down-regulated synthesis of LDL-R induced by an enhanced degradation of intra-cellular cholesterol, which might contribute to a lowering of plasma levels of LDL-C.