In a study designed primarily to assess mortality, 139 consecutive patients presenting with malignant hypertension (MHT) in Glasgow between 1968 and 1983 were matched individually for age, sex and initial blood pressure with 139 non-malignant hypertensives attending the Glasgow Blood Pressure Clinic. Fifty-four patients with MHT and 34 controls died before 1 April 1984. Multivariate analysis showed that initial serum creatinine and blood pressure achieved during treatment were significantly and independently related to outcome among the patients with MHT, but that age, smoking habit, presence of papilloedema, underlying diagnosis, initial blood pressure and year of presentation were not. Overall survival among patients with MHT was 63% at 5 years and 47% at 10 years. Although this was better than in earlier studies patients with MHT were still twice as likely to die as non-malignant controls. The excess mortality was confined largely to patients with underlying renal disease and/or renal failure at presentation. Moreover, renal failure contributed to four times more deaths among patients with MHT than controls. Thus, despite an improvement in survival compared with previous years, renal failure remains the most serious manifestation of patients with this disease.