Objectives:First, to determine the relationship between left ventricular mass (LVM) and clinic and 24-h ambulatory blood pressure parameters in normotensive renal transplant recipients. Secondly, to assess the influence of immunosuppression protocol on diurnal blood pressure and target-organ responseDesign:Measurement of supine clinic blood pressure, non-invasive 24-h ambulatory blood pressure and echocardiographically determined LVM.Patients:Twenty-eight stable, normotensive renal transplant recipients taking no antihypertensive therapy (16 cyclosporin-treated and 12 non-cyclosporin-treated). Setting: Community-based ambulatory patients reviewed in tertiary referral centre.Setting:Community-based ambulatory patients reviewed in tertiary referral centreMain outcome measures:Clinic blood pressure, mean 24-h, daytime and night-time ambulatory blood pressure and LVMResults:Mean 24-h blood pressure exceeded that recorded in the clinic. Twenty-five per cent of patients had left ventricular hypertrophy despite the absence of hypertension, and this was more common in cyclosporin-treated than in non-cyclosporin-treated patients. Mean daytime systolic blood pressure was the best predictor of LVM, being superior to clinic blood pressure and any diastolic blood pressure parameter. An attenuated nocturnal blood pressure fall ('non-dipper' pattern) was common, especially in those patients treated with cyclosporin, and was associated with higher LVM.Conclusion:In normotensive renal transplant recipients, a group at risk of cardiovascular disease, 24-h ambulatory blood pressure is closely related to the development of left ventricular hypertrophy, and may prove useful in optimizing treatment strategies to reduce cardiovascular morbidity.