A retrospective analysis of 58 patients with acute renal failure treated by hemodialysis between 1980 and 1984 was carried out to study mortality and the risk factors that might adversely influence survival. Twenty-six factors, suggested by published data to be relevant to the short-term prognosis of such patients, were evaluated by univariate analysis. Survivors were found to be significantly younger, they were less frequently malnourished or jaundiced, and fewer required inotropic drugs (due to hypotension) or ventilator support after the first week of their illness. Sepsis, heart failure, central nervous system depression, and a greater number of the above complications were characteristic in the nonsurvivors. Multivariate analysis suggests that the probability of survival could be estimated by taking into account three of these factors: age, central nervous system depression, and hypotension. Further studies would be appropriate to test the predictive value of such a probability equation.