BACKGROUND: Left ventricular hypertrophy is frequently noted in patients with moderate to severe chronic renal failure not requiring dialysis. Recently, several studies have shown reversal of myocardial hypertrophy in end-stage renal disease with long-term pharmacological control of blood pressure, but it is unclear whether left ventricular mass regresses or normalizes with antihypertensive treatment of patients with earlier stages of chronic renal failure. METHODS: Seventy-two undialysed patients with chronic renal failure, chronic mild-to-moderate hypertension, and left ventricular hypertrophy were randomly assigned in a prospective study to either the captopril (n = 36) or enalapril group (n = 36). Blood pressure measurements, echocardiographic and Doppler parameters were evaluated before treatment and at 6 and 12 months of therapy. RESULTS: During follow-up, six patients developed side-effects including dry cough, taste disturbances, skin rash and gastric intolerance. In the captopril group there was a decrease in mean left ventricular mass index by 12% after 6 months of treatment, which decreased by 20% after 12 months treatment. For enalapril, the average reduction of myocardial mass after 6 months treatment was 14% and after 12 months treatment, the decrease was 19%. In both treatment groups there was significant improvement of left ventricular filling dynamics. No deterioration of left ventricular systolic function was observed. CONCLUSIONS: Our results confirm that antihypertensive monotherapy with the ACE inhibitors, captopril and enalapril, in patients with chronic renal failure results in regression of left ventricular mass index associated with a significant improvement in the diastolic function of the left ventricle without a demonstrable deterioration in left ventricular systolic performance.