OBJECTIVE: To verify the biocompatibility between diamond-like carbon (DLC) film and human vascular endothelial cells and to provide evidences for construction of artificial mechanical valve prosthesis. METHODS: Nanophase DLC film was deposited using pulse laser deposition, while vascular endothelial cells derived from human umbilical vein was cultured with nanophase DLC film in vitro. Cell growth and adhesion were observed under inverted microscope, and cell proliferation was measured with MIT method. In addition, levels of nitric oxide (NO) and prostacyclin (PGI2) were measured in the DLC group and blank control group in order to evaluate their activities. RESULTS: Adhesion, proliferation, and growth of vascular endothelial cells derived from human umbilical vein were great on the surface of nanophase DLC film. There were no significant differences in the levels of NO and PGI2 between DLC group and blank control group (P > 0.05), showing that nanophase DLC film had no effect on activity of vascular endothelial cells derived from human umbilical vein. CONCLUSION: Nanophase DLC film has a good biocompatibility, and it can become an ideal material of tissue-engineering artificial mechanical valve prosthesis.