Some reports have shown that mesenchymalstem cells (MSCs) therapy could ameliorate chemicallyinducedhepatic fibrosis. This research assesses the therapeuticaction of bone marrow mesenchymal stem cells(BM-MSCs) on chronic diseased liver in Schistosoma mansoni infected mice. All infected female mice dividedinto three groups, one group (15 mice) treated with oralpraziquantel (PZQ), second group (15 mice) receivedintravenous injection of BM-MSCs and third group (15mice) treated with both MSCs + PZQ. Two control groups(15 mice each) subdivided into one infected and secondhealthy one. BM-MSCs were obtained from bones of bothfemur and tibia of male mice (30 mice), then cultured andcharacterized morphologically by detection of CD105 byflow cytometer. Liver tissues for all groups were examinedhistopathologically. Measuring of the collagen 1 geneexpression was done by real-time PCR and immunohistochemicalstudy to detect stem cells differentiation fordetection of MSCs engraftments in liver tissue. MSCstreatment caused marked improvement and regression offibrosis, and prevents deposition of collagen and reducedthe expression of collagen 1 gene in infected mice on theirliver tissues, especially when used with PZQ in micetreatment. It can be concluded that, MSCs is a good therapeuticmethod for liver fibrosis caused by S. mansoniinfection. Keywords MSCs _ Schistosoma mansoni _ Praziquantel _Collagen 1 gene _ OV-6