Although recent studies have demonstrated the in vitro hepatic differentiation potential of mesenchymal stem cells (MSCs), the evidence supporting the in vivo engraftment of MSCs, hepatic differentiation and improvement of hepatic function is still lacking. We investigated in vivo hepatic differentiation potential and therapeutic effect of cord blood derived-MSCs (CBMSCs) transplantation in a cirrhotic rat model. CBMSCs (2 x 10(6)) were infused in Wistar rats with thioacetamide-induced chronic liver injury. Biochemical markers, liver fibrosis and engraftment of CBMSCs were assessed. Infused CBMSCs were detected in the perivascular or fibrous region of the liver and did not acquire mature hepatic phenotypes. There was no difference in biochemical markers and in the area of liver fibrosis between the experimental and placebo groups. After infusion of CBMSCs in our experimental cirrhotic rat model we did not observe an improvement of liver function and liver fibrosis. Inversely, CBMSCs could have a pro-fibrogenic potential suggesting that a cautious approach is required in future research.