The ability of erythrocytes to resist lipid peroxidation may be a useful marker of antioxidant status in alcoholic patients, in whom depletion of dietary antioxidants may combine with increased production of free radicals to produce liver damage. There are conflicting reports, however, on the resistance of erythrocytes from alcoholic patients to lipid peroxidation. This study examined the relation between the degree of alcohol induced liver disease and the resistance of erythrocytes to chemically induced lipid peroxidation, measuring lipid peroxidation as malondialdehyde production. Erythrocytes from alcoholic patients with Child's C cirrhosis had significantly increased resistance to lipid peroxidation compared with both controls (p < 0.001) and alcoholic patients with moderate liver disease (p < 0.001). There was no difference between alcoholic patients with moderate liver disease and controls. Increased resistance to free radical initiated lipid peroxidation in alcoholic patients is related to liver damage rather than to alcohol abuse alone. This could arise from changes in the lipid composition of the erythrocyte membranes resulting from abnormal liver function. Tests of antioxidant status based upon the resistance of erythrocytes to free radical stress in vitro may therefore be flawed when such changes in membrane lipid composition can occur.