 Few studies have reported the effect of alpha1-adrenergic antagonists on 24-h blood pressure and regulation of sympathetic nervous activity in hypertensive patients with diabetic nephropathy. Using ambulatory blood pressure monitoring devices equipped with spectral analysis of heart rate variability, we assess the effects of doxazosin on blood pressure in diabetic nephropathy patients and compare the results with those in patients with essential hypertension, patients with diabetes mellitus and patients with chronic nephropathy. 