A pharmacy prescription database was used to identify patients at high risk for drug-related problems. Of the 1054 patients in the study, 687 had a diagnosis of hypertension. The utilization of antihypertensive medications was captured at three periods over 24 months (12 months before enrollment, at enrollment, and 12 months after enrollment). The diagnosis of hypertension and coexisting diseases were identified at enrollment. There were 238 (34.6%) with diabetes, 333 (48.5%) with coronary artery disease, 64 (9.3%) with congestive heart failure, and 244 (35.5%) with none of these coexisting conditions. At Period 3, 44.7% of patients without coexisting diseases received calcium channel blockers, followed closely by diuretics (41.4%). Calcium channel blockers were used significantly more frequently than any other drug category for these patients (p less than 0.05). For patients with hypertension and diabetes, ACE inhibitors were used by 62%, and this was significantly more frequently than any other category (p less than 0.03). Diuretics (52.1%) were utilized significantly more frequently than calcium channel blockers (42.9%) (p less than 0.043). For patients with hypertension and congestive heart failure, diuretics were utilized significantly more than any other category (70.3%, p less than 0.03), and ACE inhibitors were utilized significantly more often than any other category except diuretics (68.8%, p less than 0.0001). This study examined antihypertensive utilization in specific patients (rather than as a function of total drugs), making the results different from those of previous reports. This study demonstrates better adherence to recommended guidelines than previous studies have suggested. While Beta blockers and diuretics were utilized frequently in these patients, statistics suggest that there is still room for improvement in the utilization of these important drugs. This paper describes the utilization of antihypertensive medications in nine Veterans Affairs Medical Centers. (c)2000 by Le Jacq Communications, Inc.