Methotrexate (Mtx) is widely used in various cancer and inflammatory diseases. Hepatotoxicity is the most serious side effect in long-term Mtx treatment. Therefore, the present study aimed to investigate the protective effect of L-Carnitine against Mtx-induced injury in rat's hepatocytes. Fifty male albino rats, each weighing 120-130g were used. The experimental animals were equally divided into five groups , 10 rats each, and treated intraperitoneally  (twice /week) as follows : (1) rats did not receive any treatment (control group ); (2) rats given 300mg L-Carnitine /100g b.w. for 4 weeks ; (3) rats given  0.045mg Mtx /100g b.w. for 4 weeks ; (4) rats given 0.045mg Mtx /100g b.w. with 300mg L-Carnitine /100g b.w. for 4 weeks ; (5) rats given 0.045mg Mtx /100g b.w. for 4 weeks then given 300mg L-Carnitine /100g b.w. for other 4 weeks.   In Methotrexate- treated group, the ultrastructural study on hepatocytes revealed pyknotic nuclei with abnormally electron-dense chromatin, irregular nuclear envelopes, electron-dense mitochondria and fragmented rough endoplasmic reticulum.In addition to dilatation and congestion of the hepatic sinusoids as well as increase in lipid droplets and collagen fibers. Rats co-treated with L-Carnitine against Mtx showed significant improvement in the ultrastructure abnormalities of hepatocytes caused by Mtx. On the other hand, mild to moderate improvement in hepatocytes were observed in the group treated with Mtx followed by L-Carnitine. These results indicated that co- and post L-Carnitine treatment can diminish Mtx-induced liver ultrastructural injuries. The beneficial effect was more pronounced in L-Carnitine co treated with Methotrexate.