While less frequent than in the era before effective treatment for hypertension, hypertensive emergency remains a relatively common cause of hospital admission in some sub-populations. In 1989, hypertensive emergency accounted for approximately 60 admissions per year to the Medical Service at Presbyterian Hospital, and a somewhat higher proportion of intensive care unit admissions and utilization. The importance of hypertensive emergency may have been underestimated because the International Classification of Diseases discharge codes included only malignant hypertension, a severe form comprising only about half of the admissions for hypertensive emergency. There had been almost no epidemiologic studies of hypertensive emergency since 1969, and very little was known about risk factors.