OBJECTIVES To describe the clinical course of patients with endstage renal disease (ESRD) admitted to the intensive care unit (ICU) and to compare the performance of Acute Physiology and Chronic Health Evaluation (APACHE) III and Sequential Organ Failure Assessment (SOFA) in predicting their outcome. PATIENTS AND METHODS This retrospective cohort study consisted of patients with ESRD admitted to 3 ICUs between January 1, 1997, and November 30, 2002. Data on demographics, APACHE III score, SOFA score, development of sepsis and organ failure, use of mechanical ventilation, and mortality were collected. RESULTS Of the 476 patients with ESRD who underwent dialysis during the study period, 93 (20%) required admission to the ICU. The most common ICU admission diagnosis was gastrointestinal bleeding. The first day median (interquartile range) APACHE III score, SOFA score, and APACHE III predicted hospital mortality rate were 64 (47–79), 6 (5–8), and 12.9% (4.2%-30.8%), respectively. The observed ICU, hospital, and 30-day mortality rates were 9%, 16%, and 22%, respectively. Nonrenal organ failure developed in 48 patients (52%) and sepsis in 15 patients (16%). Mechanical ventilation was required in 26 patients (28%). The area under the receiver operating characteristic curve for the first-day APACHE III probability of hospital death in predicting 30-day mortality was 0.78 (95% confidence interval, 0.68–0.86) compared with 0.66 (95% confidence interval, 0.55–0.76) for the SOFA score ( P=.16). CONCLUSIONS The observed hospital mortality of patients with ESRD admitted to the ICU is relatively low. There is no statistically significant difference in the performance of APACHE III and SOFA prognostic models in discriminating between 30-day survivors and nonsurvivors.