Based on age and medical condition at the time of treatment, 138 patients beginning dialysis for treatment of chronic renal failure between January 1, 1984 and December 31, 1988, were classified into low, average, and high risk of death. The survival in these three groups was shown to be significantly different after as little as 6 months. The classification scheme is simple, and can be performed at the bedside. Efforts to monitor quality assurance in the dialysis unit must account for the significant differences in expected survival that reflect the case-mix observed in a particular unit.