We report the relationship between 24-hour (24-h) blood pressure, autonomic function, and health-related quality of life (HRQOL) in normotensives and hypertensives. The aim of this study was to determine whether there is a relationship between 24-h blood pressure, autonomic function, and HRQOL during treatment with an angiotensin receptor blocker (ARB) in patients with hypertension. Thirteen patients with hypertension were randomly treated with losartan (25-50 mg, n = 5), candesartan (4-8 mg, n = 4), valsartan (80 mg, n = 1), telmisartan (40 mg, n = 2), and olmesartan (10 mg, n = 1), daily. 24-h ambulatory blood pressure (BP) was measured before treatment and 3 months after treatment. Sympathetic nervous activity (the ratio of low frequency to high frequency component (LF/HF)) and parasympathetic nervous activity (high frequency component (HF)) were calculated by analyzing heart rate variability. HRQOL was assessed using a medical outcome study short-form 36-item health survey (SF-36) questionnaire. All of the participants completed the study. Angiotensin receptor blocker treatment reduced 24-h mean BP (MBP) from 107 +/- 9 to 100 +/- 9 mmHg. 24-h MBP positively correlated with 24-h LF/HF in all subjects who received ARB (R = 0.568, p < 0.04). There were no differences in heart rate, serum albumin level, BUN level, creatinine level, potassium level, or HRQOL score. These findings indicated that ARB reduced BP; however, treatment with ARB did not affect the scores of HRQOL and the relationship between 24-h blood pressure and autonomic function.