Rhabdomyolysis causes renal dysfunction associated with renal vasoconstriction, tubular toxicity and luminal obstruction. There is now accumulating evidence that renal injury, caused by lipid peroxidation, is important in the pathogenesis of renal failure. The proposed central role of free iron in this process is examined. Current data have shown that the heme center of myoglobin can initiate lipid peroxidation and renal injury without invoking release of free iron, and this process is due to redox cycling of the heme group from ferrous to ferric and to ferryl oxidation states. Alkaline conditions prevent myoglobin-induced lipid peroxidation by stabilizing the reactive ferryl myoglobin complex. This review explores the evidence for each of these mechanisms.