Doxorubicin (DOX) is an antitumor drug that causes hepatotoxicity by release of free radicals and injury of the liver tissues. Nano-thymoquinone (nano-TQ) is considered a potent antioxidant that abrogates hepatotoxicity. The aim of the current investigation was to assess the liver toxicity of DOX and the protective effects of nano-TQ on chronic hepatotoxicity in male rats. Sixty rats were divided into four even groups: DOX treated group (group 1) received 3.750 mg/kg b.wt. intraperitoneally at days 10,17,24 and 31 from the beginning of the experiment to make a cumulative dose of 15 mg/kg b.wt., Group (2) received DOX as group 1 beside nano-thymoquinone daily from day one in a dose of 10 mg/kg b.wt. until the end of the experiment, Group (3) received nano-TQ only, group (4) is considered a negative control group. Serum samples were used for estimating oxidative stress markers and liver function enzymes. Liver specimens were used for histopathological and Transmission electron microscopic (TEM) examination. Doxorubicin administration induced an increase in liver enzymes and lipid peroxidation products. Nano-TQ treatment improved those altered parameters. Microscopic examination of the DOX-treated liver sections revealed vascular and parenchymatous alterations as congestion, thrombosis of the blood vessels, vacuolar degeneration, hepatocellular necrosis and fibrosis of the liver. While nano-TQ improved such pathological alteration of the hepatic parenchyma. Transmission electron microscope of the liver revealed infiltration of lymphocyte in the necrotic areas and presence of fat globules in the cytoplasm of the hepatocytes in DOX treated group while TEM revealed a unique finding in DOX and nano-TQ treated group expressed by hypertrophy of Kupffer cells. It could be concluded that nano-TQ has a potent antioxidant effect that protected the liver damage via its free radicals scavenging protection.