Production and usage of multi-walled carbon nanotubes (MWCNTs) have widely increased over the last years. Nanoparticles with their sizes below 100 nm are able to enter and be stored in organs (such as liver, lung, testes and brain) and caused toxic effects. The aim of the present study is to investigate the MWCNTs toxicity, if any, on liver tissue. A total number of fifteen male albino rats were used in the present study; five rats as control and ten rats were intravenous injected with a single dose of MWCNTs (30 mg/ kg body weight, 20-50 nm in diameter and 1 µm in length). Histopatholgical, histochemical, apoptotic, necrotic and ultra-structure studies were carried out in the present work. The results showed different histopathological changes on liver tissues of MWCNTs-treated rats, such as focal hepatic necrosis with inflammatory cells infiltration, hydropic degeneration of hepatocytes, and some increases in collagen fibers deposition in the portal area after 28 days of MWCNTs injection. High appearance of necrotic and apoptotic cells was also noticed. Ultrastructure study of liver tissue of rats treated with MWCNTs showed abnormal hepatocytes with irregular nuclear envelope and nuclear chromatin material, swollen and fused mitochondria with destructed cristae, lysis of some cytoplasmic organelles and rupture of the endoplasmic reticulum. Shrunken nucleus and abundance of vacuoles and lysosome were also observed in the hepatocytes. It could be concluded that MWCNTs have a toxic effect on liver tissue and hepatocytes of rats.