Abstract: Objective To compared the differentiation capacity of rat adipose-derived stem cells (ASCs) and bone marrow mesenchymal stem cells (BMSCs) into endothelial cells. Methods Rat BMSCs and ASCs were isolated, cultured and identified for cell surface markers using flow cytometry. The cell growth curves were drawn by CCK-8 assay, and the cells in active growth were induced for endothelial differentiation following standard protocols. On day 21 of induction, the cells were examined for mRNA expressions of endothelial cell specific markers CD31, KDR, and vWF using qPCR. Immunostaining was performed to observe the expression of CD31 on the cells. The induced cells were also tested for Dil-labeled acetylated low-density lipoprotein (ac-LDL) uptake ability. The tube-forming ability of the induced cells was verified on Matrigel. Results We successfully isolated rat ASCs and BMSCs. Morphologically, ASCs were similar with BMSCs, both having long spindle-shaped and fibroblast-like morphology. Flow cytometry showed that both BMSCs and ASCs had high expressions of mesenchymal markers CD29 and CD90 and a low expression of hematopoietic cell surface markers CD45. CCK-8 assay showed that ASCs proliferated more quickly than BMSCs. The cells with induced endothelial differentiation exhibited increased levels of CD31, KDR, and vWF mRNA expressions and immunofluorescent staining identified CD31 antigen expression on the cell membrane. Fluorescence microscopy revealed red fluorescence in the induced cells suggesting uptake of Dil-Ac-LDL by the cells. The induced cells were capable of forming tube on Matrigel, confirming their identity of endothelial cells. Conclusion Both rat BMSCs and ASCs can be induced to differentiate into endothelial cells, but ASCs differentiate more quickly into endothelial cells and possess a stronger proliferation ability, suggesting its greater potential than BMSCs in future applications.