Falcaria vulgaris locally named Paghazah has been used traditionally as a herbal medicine The aim of this experiment was to supplementary study on the VASODILATATION EFFECT of the plant extract, role of the nitric oxide in this action and the potential cytotoxic EFFECT of this herbal medicine on the isolated rat heart. In this study, hearts of male NMRI rats were isolated and perfused under constant pressure according to Langendorff method. Extract of the plant was prepared by soaking it in 70% ethanol according to percolation method. The rats were assigned into three groups. In one group (n=8) concentrations of 0.2, 1 and 5 microgram/ml of the extract were infused into the hearts over a period of 5 minutes and different cardiac parameters were measured and recorded. In the second group (n=8) 15 and 22.5 mg of the extract were used as bolus injections by ten minute intervals. Then the above mentioned doses were injected again into the hearts treated with LNAME (100micmol). In the third group, at first the hearts were treated with LNAME, then 15 mg and 22.5 mg of extract were injected. Results of this study showed that infusion of concentrations of 0.2, 1 and 5micgr/ml of the extract significantly increased coronary solution flow (CSF) (P<0.05). Following injection of 15 and 22.5 mg of extract, CSF increased significantly from 10.58±0.63 and 9.66±0.52 ml/min to 13.76±0.51 and12.18±0.64 respectively (P<0.05). Also similar significant increases in CSF changes were seen in the presence of LNAME (P<0.05). Amount of LDH released after bolus injection of the extract did not significantly differ from its amount in the control group. In conclusion, in the present study we emphasize the coronary vasodilator EFFECT of Falcaria vulgaris hydro alcoholic extract in the isolated rat heart. Nitric oxide is not involved in this action. Also on the basis of LDH measurement it has no cytotoxic EFFECT.