We analyzed hospital survival rates, severity of illness, and long-term outcomes in patients from three different age groups who were treated with hemodialysis for acute renal failure (ARF). Patients over age 80 had fewer bad prognostic factors. This selection bias was reflected in their hospital survival rates of 53%, compared to 57% of patients under age 70. No selection bias for patients ages 70 to 79 years was identified, and their hospital survival rate was 27%. The long-term outcome of hospital survivors was poor, particularly in the very elderly. Physicians should consider all of these factors when deciding whether to offer hemodialysis to elderly patients suffering from ARF.