In order to evaluate the effect of Cordyceps sinensis (CS) on aminoglycoside (AG) induced nephrotoxicity, gentamycin was imposed on the young and old rats with CS administration. The renal tubular injury was ameliorated as evidenced by less prominent increment of BUN, SCr, sodium excretion, urinary NAGase and less severity of histopathological changes as compared with control. In addition, the use of CS could promote an earlier recovery of renal oxygen consumption insulin clearance, and sodium absorption in isolated perfused kidney from CS treated intoxicated rat than that from control. Possible mechanisms of CS on drug-induced nephrotoxicity include: (1) Accelerating the regeneration of tubular cells; (2) Protecting the sodium pump activity of tubular cells; (3) Attenuating the tubular cell lysosome hyperfunction stimulated by phagocytosis of AG as well as decreasing the tubular cell lipoperoxidation in response to toxic injury; (4) Reducing the tissue Ca++ content.