Ginseng extract and its active component, saponin, were administered orally to nephrectomized rats for 90 d, and changes in blood and urine parameters and renal tissue lesions were assessed. Rats given saponin showed a significant decrease in the concentrations of blood urea nitrogen, creatinine and methylguanidine and a significant increase in total protein and albumin in the blood, with reduced urinary excretion of protein. There was also slight amelioration of the degree of mesangial proliferation, the severity of extratubular lesions and glomerular sclerotic lesions, and the extent of tubular interstitial lesions. However, these histological changes were inconspicuous in nephrectomized rats given ginseng extract.