The effects of 3-deaza-adenosine on the cardiovascular system was investigated in normotensive (WKY) and spontaneously hypertensive rate (SHR). This compound (50 mg/kg i.p. 2X) significantly lowers blood pressure in both groups of animals, an effect which lasts for up to 2 h. The hypotensive effect is not affected by ganglion blockade, and appears to be due in part to a direct effect on blood vessels. While the response is similar to that seem with adenosine, it is more long-lasting. The results of this study suggest a potential role for this compound or analogues of its as possible antihypertensive agents.