Acute renal failure occurs frequently, may be increasing, carries an unacceptably high mortality, yet there is no specific treatment. The induction of stress response (heat shock) proteins (HSPs) is a highly conserved response that protects many cell types from diverse physiological and environmental stressors. HSP families of different sizes function as molecular chaperones that facilitate the folding of enzymes and other proteins into functional conformations. After injury, HSPs are believed to facilitate the restoration of normal function by assisting in the refolding of denatured proteins and degradation of irreparably damaged proteins and toxic metabolites, limitation of aggregation of damaged peptides and aiding appropriate folding of newly synthesized essential polypeptides. HSPs may also regulate apoptosis and immune functions. We have demonstrated protection from the functional deficits and histological evidence of experimental ischemic renal injury with heat stress 6 but not 48 h prior to ischemia. Limitation of the induction of HSPs (either with a short period of hyperthermia or pharmacologically) attenuated the protection observed. Other investigators have demonstrated a correlation between the levels of HSP25 and renal ischemic preconditioning in the mouse. Several pharmacological agents have been shown to increase HSP expression. Enhancement of these endogenous protective mechanisms has potential benefit in human disease.