Left ventricular hypertrophy (LVH), which frequently occurs in chronic uremia, may be due in part to factors other than arterial hypertension, chronic anemia, and/or other well-known loading conditions inherent to the uremic state. Angiotensin-converting enzyme (ACE) inhibitors may be able to reverse LVH by mechanisms independent of their antihypertensive effects. In this study, 18 subjects free of arterial hypertension or severe anemia were selected from 170 chronically hemodialyzed uremic patients after fulfilling the criterion of a supranormal left ventricular mass (LVM). Ten subjects agreed to undergo treatment with 2.5 to 20 mg lisinopril every other day over a period of 2 years, during which annual determinations of the LVM by echocardiography and of the 24-hour blood pressure with a portable device were carried out. Eight patients unwilling to undergo the treatment served as controls. The average resting left ventricular mass index (LVMi) of the overall group was 178 +/- 30 g/m2 body surface area (+/- SD), and did not differ between the two subgroups. Lisinopril treatment significantly decreased the LVM of eight of 10 treated subjects and actually even completely normalized it in three. The LVM of the untreated group remained unchanged. Systolic and diastolic blood pressures were 138 +/- 5 mm Hg and 78 +/- 6 mm Hg in the treated group and 133 +/- 9 mm Hg and 75 +/- 4 mm Hg in the untreated group, respectively (P = NS), and did not vary over the following 2 years. This study indicates that a mild degree of LVH, which is seemingly independent of arterial blood pressure load, does exist in a tight subset of uremic patients. This study also demonstrates that this type of LVH is apparently nonprogressive. ACE inhibitors given at doses not affecting blood pressure are able to reverse it.