Sixty patients out of 1,844 recovery room admissions had significant postoperative arterial hypertension. Nearly 60% of them had a history of hypertension. The postoperative hypertension usually began within 30 min from the end of operation and lasted about 2 hours. In 20% of the patients it lasted 3 hours or longer. Complications attributable to hypertension were confined to this latter group. The principal factors possibly contributing to the pressure elevations were pain (35%), hypercarbia (15%) and emergence excitement (16%). Ten of the patients (17%) had no demonstrable cause for hypertension. The hypertension in this group appeared to have a shorter and more benign course.