The effect of angiotensin-converting enzyme (ACE) inhibitors on ischemia-induced spatial dispersion of ventricular repolarization was investigated in 12 pentobarbitone-anesthetized sheep. The obtuse marginal coronary artery was occluded in the pretreated animals (enalapril maleate, 0.4 mg/kg, i.v., n = 6) and controls (normal saline, i.v., n = 6). The activation-recovery intervals were determined from the unipolar ECGs acquired from the ischemic region. There was a significant increase in the pooled activation-recovery interval dispersion in both groups at 30 min of coronary occlusion (p < 0.01), however, the increase in the treatment group was smaller than that of the controls (15.9 ± 9.7 vs. 43.6 ± 19.9 ms, p < 0.01). Ventricular ectopic beats were observed in the 6 controls and in only 1 pretreated animal. Conclusions: ACE inhibitors suppress the spatial dispersion of ventricular repolarization and this may be attributed to, at least in part, its antiarrhythmic effect.