BACKGROUND It is not known whether strict control of blood pressure (BP) in mild post-transplant hypertension gives any benefit. Our primary objective was to test the antihypertensive effects of lisinopril added to standard therapy on ambulatory BP (ABP) of post-transplant patients. The secondary objective was to monitor echocardiographic and hemodynamic end points. METHODS Post-transplant patients with an abnormality of the 24-h ABP recording were recruited to this double-blind randomized prospective study that started 2 to 3 months after transplantation. Patients were then evaluated at 6, 12, 18, and 24 months after transplantation. RESULTS Lisinopril decreased the clinic BP and ABP, the latter from 134/85 to 126/82 mm Hg at 6 months (P =.01 v placebo) and 121/79 mm Hg after 2 years (P =.03 v placebo). Fewer patients in the lisinopril group required added amlodipine to control the BP (P =.01). Data on left ventricular (LV) mass are difficult to interpret because by coincidence in this small study, the lisinopril group had lower initial values than placebo. However, in the lisinopril group mean LV mass decreased by 10% (P =.02) and mass index by 13% (P =.01), whereas placebo LV mass and index did not change. The LV end-diastolic diameter increased only in the placebo group (P =.008). There were no significant changes in any of the other secondary outcomes, including the cardiac index and systemic vascular resistance. CONCLUSIONS Thus, in these post-transplant patients, stricter BP control to normal levels by the addition of lisinopril to existing therapy, reduced BP and modestly decreased LV mass without altering cardiac hemodynamic function.