Since left-ventricular hypertrophy (LVH) has been identified as a poor prognostic indicator in patients with secondary hypertension, we investigated 38 renal transplant recipients on antihypertensive medication with 24-h ambulatory blood-pressure measurement (SpaceLabs 90207) and determined their left-ventricular mass by two-dimensional guided M-mode echocardiography. An increased left-ventricular mass correlated with a reduced fall of diastolic blood pressure during sleep (r = 0.29; p less than 0.05), as well as with a reduced fall of mean arterial pressure during sleep (r = 0.31; p less than 0.05). Therefore, a less pronounced afterload during sleep is related to more severe left-ventricular hypertrophy, suggesting a worse cardiovascular prognosis.