Circadian blood pressure pattern in the patients with chronic glomerulonephritis was studied by ambulatory 24-hour blood pressure monitoring (ABPM). Subjects were 32 patients and were divided into three groups with various renal function; Ccr of 10 patients were normal (Ccr > or = 70 ml/min), 10 patients 30 < or = Ccr < 70 ml/min and the Ccr were below 30 ml/min in the other 12 patients. Blood pressure levels were significantly higher in reduced Ccr groups as compared with normal Ccr cases. The blood pressure gradient between day-time (7:00-19:00) and sleeping time (1:00-5:00) significantly decreased in the patients with renal impairment as compared with normal Ccr cases. And it positively correlated with Ccr (r = 0.51, p < 0.01). These results indicate that the patients with reduced renal function in chronic glomerulonephritis show abnormal circadian blood pressure pattern and nocturnal hypertension, which may require novel modification of antihypertensive treatment.