This longitudinal study was performed in order to clarify the effects of long-term antihypertensive medication on common carotid hemodynamics. A total of 84 patients (54 males and 30 females), who had been receiving treatment with antihypertensive medications for 5 years, were enrolled in this study. The subjects' ages ranged from 62 to 74 (mean 67). They were divided into three groups: 40 were treated with diuretics only (Group D), 28 with calcium antagonists only (Group C), and 16 with angiotensin converting enzyme inhibitors only (Group A). Mean blood flow volume (BF) and circulation resistance (Z) at the common carotid artery were measured by an ultrasonic quantitative flow measurement system. Blood flow volume, Z, and mean blood pressure (MBP) were measured twice over a 5-year period in patients and in 49 age-matched normal controls (Group N). Annual reductions in BF (delta BF) and MBP (delta MBP), and annual increases in Z (delta Z) were calculated. Blood flow volume of Group D showed larger decreases than that of the other three groups. Circulation resistance of Group C showed smaller increases than that of Group N. Reductions of BF and Z of Group A were similar to those of Group N. Reductions of Z of Group C showed a significant correlation with delta MBP. These results indicate that calcium antagonists may have beneficial effects on common carotid hemodynamics in elderly patients with essential hypertension.