Defatted milled grape seed (DMGS) is a wine by-product obtained from the oil extraction of the grape seed that contains different types of phenolic compounds. The present study was designed to evaluate the possible protective effect of DMGS on toxicity induced by adriamycin (ADR) in isolated rat hepatocytes. The study was carried out by examining the results of lactate dehydrogenase (LDH) release to estimate cytotoxicity; the thiobarbituric acid reactant substances (TBARS) and carbonyl group levels were measured as biomarkers of oxidative stress and ATP and GSH levels as estimation of intracellular effect. The results showed that DMGS extract protects the cellular membrane from oxidative damage and consequently prevents protein and lipid oxidation. The levels of ATP and GSH changes for the ADR toxicity were restored to control value in the presence of DMGS extract. The experimental results suggest that this wine by-product may be used to decrease oxidative stress.