Diazepam and chlorpromazine - psychotropic agents widely used for the amelioration of anxiety, depression, and psychosis, have been found to affect cell proliferation. We have checked whether these drugs influence proliferation of endothelial cells and probably angiogenesis process. We have studied the effect of diazepam and chlorpromazine on proliferative activity and vascular endothelial growth factor (VEGF) release from murine endothelial HECa10 cells cultured in vitro. In conclusion, diazepam at concentration of 10(-4)M had inhibitory action on the proliferation of endothelial cells in cultures. Chlorpromazine at concentrations from 10(-7) to 10(-4)M diminished the proliferative activity and secretion of VEGF into supernatants of cultured cells.