Cardiac reinnervation late after heart transplantation has been reported in individual patients. As a measure for reinnervation, circadian changes in arterial blood pressure and heart rate have been used but not yet systemically evaluated in cardiac transplant recipients. Ambulatory blood pressure and heart rate monitoring was performed in 62 patients for 24 hr early (<6 months, mean 26 days, range 5-90 days, n=30) and late (> or = 6 months, mean 12 months, range 7-78 months, n=32) after heart transplantation. A loss of physiological nocturnal decline in blood pressure and heart rate was noted early after transplantation, whereas late after operation an improvement in circadian changes of blood pressure and heart rate was observed. The patients late after heart transplantation had a significant higher diastolic blood pressure. A pathological circadian blood pressure and heart rate pattern was observed in patients early after heart transplantation, which was improved late after operation. This could be explained by partial reinnervation of the heart. Diastolic hypertension late after transplantation may be due to cyclosporine treatment and/or neuroendocrine hyperactivity.