The safety and efficacy of angiotensin converting enzyme inhibition (ACEI) after heart transplantation (HT) is unknown. This study examined long-term clinical outcomes after ACEI in HT recipients.The ACEI after HT study was a prospective, randomized trial that tested the efficacy of ACEI with ramipril after HT. In this study, long-term clinical outcomes were assessed in 91 patients randomized to either ramipril or placebo (median, 5.8 years). The primary endpoint was a composite of death, retransplantation, hospitalization for rejection or heart failure, and coronary revascularization.The primary endpoint occurred in 10 of 45 patients (22.2%) in the ramipril group and in 14 of 46 patients (30.4%) in the placebo group (Hazard ratio (HR), 0.68; 95% CI, 0.29-1.51; P = .34). When the analysis was restricted to comparing patients who remained on a renin-angiotensin system inhibitor beyond 1 year with those who did not, there was a trend to improved outcomes (HR, 0.54; 95% CI, 0.22-1.28, P = .16). There was no significant difference in creatinine, blood urea nitrogen, and potassium at 3 years after randomization. The cumulative incidence of the primary endpoint was significantly higher in patients in whom the index of microcirculatory resistance increased from baseline to 1 year compared with those in whom it did not (39.1 vs 17.4%, HR: 3.36; 95% CI, 1.07-12.7; P = .037).The use of ramipril after HT safely lowers blood pressure and is associated with favorable long-term clinical outcomes. Clinical Trial Registration-URL: https://www.clinicaltrials.gov. Unique identifier: NCT01078363.