Summary:A prospective ten‐year follow‐up study at the Cardio‐Vascular Clinic, Sydney Hospital, of patients under the age of 60 years with severe hypertension, diastolic blood pressure of 110 mm Hg, is reported. The ten year mortality rate was 51%. The adverse prognostic significance of the male sex, high diastolic blood pressure, advanced retinopathy, impaired renal function, gross cardiac enlargement, marked left ventricular hypertrophy and the presence of cardiac and cerebral complications was confirmed. Age of patient, duration of hypertension, aetiological diagnosis, positive family history and the presence of non‐specific symptoms such as head‐ache were of little prognostic significance.The five‐year mortality pattern in two consecutive groups of 100 patients first seen in 1955 and 1960 was compared. There has been improvement in the overall prognosis of hypertensive patients during the past decade. There appears to have been a reduction in the prevalence of accelerated hypertension as well as prolonged survival of patients with the acute form of the disease. A marked drop in mortality due to cerebrovascular accidents has been observed. The number of deaths due to myocardial infarction seems to be increasing in spite of apparently better hypotensiv