Abstract: Objective: To investigate the relationship between circadian rhythm and target-organ damage in the elderly with blood pressure high-normal.Methods: Twenty-four hours ambulatory blood pressure monitoring profiles were recorded in all subjects.According to the results of ambulatory blood pressure monitoring,86 subjects with blood pressure high-normal were divided into two groups:normal circadian rhythm group(n=55) and abnormal circadian rhythm group(n=31).Urinary microalbuminuria(mAlb) was determined by radioimmunoassay and intima-media thickness of carotid artery(IMT) was measured by high resolution colour Doppler ultrasonography.All the subjects were performed ultrasonic cardiography.The left ventricular mass index(LVMI) was calculated according to the Devereux formula.Results: The abnormal circadian rhythm group had higher mAlb,IMT and LVMI than the normal circadian rhythm group(P<0.01 and P<0.05).Conclusions: Abnormal circadian rhythm of blood pressure indicates the possibility of more severe target-organ damage in the elderly with high-normal blood pressure.