Individuals who do not have a 10% to 20% reduction in blood pressure (BP) during the night are known as ‘nondippers’. Non-dipping patterns in hypertensive patients have been shown to be associated with an excess of target organ damage and other adverse outcomes. The present study was designed to investigate the relationship between nocturnal BP pattern, defined on the basis of the ambulatory blood pressure monitoring (ABPM) recording, and cardiac and renal target organ damage in a population of at least one year treated essential hypertensive subjects. The present analysis involved 123 patients with treated essential hypertension attending the outpatient clinic of our centre. Each patient was subjected to the following procedures: blood sampling for routine blood chemistry, spot urine for proteinuria, 24-hour periods of ABPM, and echocardiography. In the ABPM period, a dipping pattern was observed in 65 of the 123 patients, and a non-dipping pattern in 58 patients. Body mass index was higher in the non-dippers (26 ± 4 versus 28 ± 4, p<0.05). The proteinuria in spot urine was significantly higher in the non-dippers (10 ± 6 versus 24 ± 48, p<0.03). Left ventricular mass, interventricular septum thickness, posterior wall thickness and left ventricular systolic diameter were significantly higher in the non-dippers compared to the dippers. Left ventricular diastolic function was similar in non-dipper cases, except E-wave deceleration time. In treated essential hypertensives the blunted or absent nocturnal fall in blood pressure can be a strong predictor of cardiac and renal events. Hypertensive patients should be evaluated by ambulatory blood pressure monitoring. To prevent patients at risk for morbidity and mortality casualities as a result of hypertension, patients should be evaluated by ambulatory blood pressure monitoring. This method can be utilized for exacting future follow-ups with the patient.