Hypertension associated with ciclosporin A may be mediated by sodium and volume retention. Therefore, the effects of an antihypertensive therapy (6 weeks) with nitrendipine (10-20 mg twice daily) or lisinopril (10-20 mg once daily) on office blood pressure, 24-hour ambulatory blood pressure, and left ventricular function were evaluated in a randomised, double-blind cross-over trial in patients after heart transplantation. Nitrendipine and lisinopril were equally effective in lowering office and ambulatory systolic and diastolic blood pressures. After an acute sodium load (210 mval/2 h i.v.), sodium excretion was significantly increased during therapy with lisinopril but only slightly during nitrendipine, indicating that angiotensin-converting enzyme inhibition may improve the sodium-retaining state of heart transplant recipients associated with ciclosporin A.