P19 embryonal carcinoma cells were examined under different conditions of embryoid body (EB) formation to evaluate endothelial differentiation. A prominent capillary-like network including PECAM-1 positive cells and upregulated expression of endothelial markers Tie-1, Tie-2, Flk-1 and PECAM-1 were identified in the DMSO-treated group during EB formation as well as after VEGF treatment. About 4% of the P19 cells differentiated into PECAM-1 positive cells on day 14 of differentiation. These results suggest that the P19 cells have the potential for endothelial cell differentiation and provide a new model system for future research.