To evaluate the effect of the saponin of heat-processed ginseng (Sun ginseng, SG), we investigated the protective effect of SG total saponin fraction against adenine-induced chronic renal failure in rats. SG saponin significantly decreased the levels of urea nitrogen and creatinine in the serum, but increased the urinary excretion of urea nitrogen and creatinine, indicating an improvement of renal function. SG saponin also inhibited adenine-induced kidney hypertrophy and edema. SG saponin reduced serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactate dehydrogenase activities increased by adenine. Based on these findings, the ameliorating effect of SG on chronic renal failure may result from its saponin.