The purpose of this study was to define the outcome of patients receiving both renal replacement therapy and mechanical ventilation in 16 Scottish intensive care units over a 2-year period. Patients were identified from the Scottish Intensive Care Society's database. Survivors developing end-stage renal failure were identified after examination of the Scottish Renal Registry's database. Mortality was 64.2% (392/612) for all patients receiving renal replacement therapy and mechanical ventilation. End-stage renal failure developed in 1.6% (3/188) of the survivors of acute renal failure and in 33% (4/11) of the survivors with pre-existing chronic renal failure. Mortality has not improved when compared with earlier studies. End-stage renal failure rarely develops following acute renal failure in the intensive care unit.