A radomized controlled trial was conducted in a metropolitan teaching hospital to determine whether improving follow-up of emergency room patients who had hypertension led to improvements in their medical care and blood pressure control. One hundred fourty four patients were randomly assigned into an intervention group and a control group. In the former, a follow-up clerk assigned patients in returning for follow-up care. Eighty-four percent of patients in this group and 63% of control patients returned to the clinic (P less than 0.1). However, five months after the patients' emergency room visits, 51% of patients in the intervention group and 53% of control patients were normotensive. There were more diagnostic and therapeutic measures in the intervention group, but long-term management was similar in both groups. Improvement in follow-up may not be by itself lead to blood pressure control among hypertensive patients.