Alterations in the content of lipids and phospholipids were studied in rat liver mitochondrial membranes after long-term heating at 37 degrees, pH 7.4, using FeSO4-ascorbate as inductors of lipid peroxidation. Under these conditions, activation of lipid peroxidation in mitochondrial membranes led to a marked increase in the rate of hydrolysis of phosphatidylethanolamine and lysophosphatidylethanolamine, to elevated synthesis of phosphatidylserine, sphingomyelin, phosphatidic and lysophosphatidic acids, diglycerides and cholesterol esters as well as to inhibit hydrolysis of phosphatidylcholine, cardiolipin and their lyso-derivatives.