Recent in vitro studies suggest that angiotensin converting enzyme (ACE) inhibitors stimulate endothelial cell proliferation and migration. The present study was designed to test the hypothesis that an ACE inhibitor may accelerate endothelial regrowth in vivo. Twenty eight New Zealand White rabbits were randomized to receive placebo or the ACE inhibitor perindopril and underwent iliac balloon denudation. Endothelial regrowth, quantified 28 days after injury using Evans blue, was significantly greater in perindopril-treated animals than in controls (131 +/- 9 mm2 vs 69 +/- 8 mm2; P < .001). These results were confirmed by scanning electron microscopy and by specific immunostaining for endothelial cells. These data provide the first in vivo demonstration that ACE inhibitors accelerate endothelial regrowth after arterial injury. This effect may contribute to the benefit observed with ACE inhibition following arterial injury.