They found those who took the drug Darusentan, even at various doses, saw a substantial reduction in blood pressure.
Experts say the drug could potentially take hypertension sufferers, at high risk of heart attack and stroke, into a low risk zone.
They warn that a major side effect of Darusentan was excess fluid accumulation in the body, so patients who take the drug should be on diuretic therapy.
Gilead Sciences, the maker of Darusentan, is expecting the results of a second study to bolster their claim and apply for FDA approval by late 2010.
Results of the trial are published online in the Sept. 13 edition of The Lancet.