The aim of the study was to compare the diurnal pattern of blood pressure in diabetic patients with normal urinary protein excretion, microalbuminuria and end stage renal failure due to diabetic nephropathy and on continuous ambulatory peritoneál dialysis. An ABPM-oscillometric blood pressure monitor was used. Cholesterol, triglicerides, HDL and LDH1 cholesterole, apolipoprotein A1 and B, endogenous creatinine urinary protein and albumin excretion, beta-2-microglobulin were measured. The mean age and the mean diabetes duration of the 12 normoalbuminuric patients 38.3 and 16.5 years, of the 12 patients treated for renal failure with continuous ambulatory peritoneál dialysis 54.4 and 19.5 years. In the group with end stage renal failure and continuous ambulatory peritoneál dialysis, the mean nocturnal and diurnal systolic and diastolic blood pressure and the average arterial mean pressure was significantly higher than in the normal and microalbuminuric groups. In microalbuminuric and dialysed patients the physiological nocturnal decline of arterial blood pressure was absent. 24 hour blood pressure monitoring may accurately identify the early stage of diabetic nephropathy, and it might be valuable in the correction of antihypertensive treatment from the early to the final stages of diabetic nephropathy.