Hospitalization may afford an excellent opportunity to maximize recognition and control of the hypertensive patient and ensure medical follow-up. We reviewed records of 536 medical or surgical patients consecutively admitted to a university hospital to assess trends in hypertension-related medical care according to guidelines established by the 1984 report of the Joint National Committee (JNC III) on Hypertension Detection, Treatment, and Control. Of 143 hospitalized patients considered hypertensive, 70% were controlled on admission, and 77% were controlled at hospital discharge. No significant differences were found in control status when medical and surgical patients were compared. Of 52 medical patients with hypertension, two lacked a documented diagnosis of hypertension at discharge compared to 16 of 94 surgical patients with hypertension (P less than 0.05). Nine of the 16 undiagnosed surgical patients were also uncontrolled at discharge. Of 43 medical or surgical patients who entered the hospital uncontrolled, 19 (44%) remained uncontrolled at discharge. Seventy percent of patients with uncontrolled hypertension entered the hospital on antihypertensive drugs, and there was no net increase in antihypertensive drug use in these patients during hospitalization. These data suggest that physicians frequently fail to capitalize on hospitalization as an opportunity to diagnose and control hypertension in some patients. Our results indicate that surgeons may be less attentive than internists to diagnosis of hypertension. In addition, hospitalization remains a setting in which medical care for hypertension could be improved.