The objective of the present study was to examine the effect of angiotensin-(1-7) 〔Ang-(1-7)〕 on coronary flow and cardiac function in isolated guinea-pig hearts. The isolated guinea-pig heart was perfused in a Langendorff mode. Coronary flow, heart rate, left ventricular pressure and its first derivatives (±dp/dtmax) were recorded. Results showed that Ang-(1-7) (100 or 300 nmol*L-1) caused an increase in coronary flow and an impairment in cardiac function in isolated guinea-pig hearts. Indomethacin, a cyclooxygenase inhibitor, did not affect the effect of Ang-(1-7). However, the increased coronary flow by Ang-(1-7) was abolished by pretreatment of Nω-nitro-L-arginine-methyl-ester, a nitric oxide(NO) synthase inhibitor. These results suggest that Ang-(1-7) increases coronary flow and reduces cardiac function, and that the vasodilating action is related to stimulation of NO release.