Objective: To study the out-of-hospital quality of life and long-term survival of critically ill patients with combined multiple organ failure and acute renal failure treated with continuous renal replacement therapy (CRRT). Design: Study based on responses to postal questionnaire and clinical information obtained during treatment in the intensive care unit (ICU). Setting: ICUs of two tertiary institutions. Patients: 85 survivors from a pool of 250 patients with combined acute multiple organ and renal failure who were treated with CRRT. Method and results: Anonymous postal questionnaire based on an activity index, mental function index, and a simplified version of the Nottingham Health Profile. Of the 250 patients, 85 (34%) survived to be discharged from hospital: 57 males (67%) and 28 females (33%), mean age 56.9 years (range 13.4-81). Mean duration of ICU stay was 10.9 days (range 2-52), mean admission Acute Physiology and Chronic Health Evaluation II score was 24.2 (range 15-41), and mean duration of CRRT was 6.2 days (range 1-34). Mean follow-up time was 2.5 years (range 0.1-5.3). Thirty-three of the 85 patients (38.8%) did not reply to the questionnaire; 35 patients (41.7%) were alive at the time of response and 17 (20%) were deceased. Of the 35 responders, 68.5% were satisfied with their present slate of health, despite 60.6% stating that their mobility had been affected, with 41.9% being unable to walk more than 200 metres. Most (94.5%) survivors, however, felt that their treatment had been worthwhile, and 91.2% said that they would undergo the same treatment again if necessary. The approximate cost for each year of survival was U.S. $50,000. Conclusions: In the majority of patients who survived to be discharged from hospital after combined acute multiple organ and renal failure, the overall state of health and quality of life seemed acceptable. Most patients felt that their treatment was worthwhile and that they would undergo the same treatment again if necessary. Our findings suggest that the cost and effort associated with CRRT and ICU care in these patients are high but broadly comparable to those associated with the care of other serious illnesses. They are also seen as worthwhile by survivors, who consider their life to be of acceptable quality.