and short survival time causes a serious worldwide health burden. Chemotherapy as 5-Flourouracil (5-FU) is used as the first-choice treatment for HCC, however it is associated with resistance, low efficacy and has side effects. Consequently, the administration of mesenchymal stem cells (MSCs) as a novel therapy for HCC holds great promise. MSCs can differentiate into hepatocytes, reduce liver inflammation, promote hepatic regeneration and secrete protective cytokines. This is the first study that sheds new light on the role of MSCs alone or together with 5-FU in HCC. In this study, Bone marrow derived-MSCs were prepared and HCC model was induced via treating rats with N-diethylnitrosamine (DEN). The effect of treatments was evaluated by biochemical, tumor markers, macroscopical, and histopathological analysis. Also, cell cycle, apoptosis assay, KI67 and CD95 were performed by Flowcytometry. The administration of MSCs together with 5-FU yields a decrease in the liver enzymes with down-regulation of tumor markers as well as improvement of histopathological picture. In addition, such treatment decreased cell proliferation that associated with the down-regulation of KI67 expression. Furthermore, MSCs did not mediate the apoptosis pathway together with reduction of CD95 expression and cell cycle arrest at G0/G1 phase. In conclusion, MSCs exerted antitumor effects by inhibiting proliferation, modulating the cell cycle in G0/G1 phase and improved the toxic effect of 5FU via improvement of liver enzymes and decreased tumor markers.