This was a retrospective chart review of consecutive obese patients admitted to the medical intensive care unit. Patients were divided into 2 groups: mild to moderately obese (group 1, body mass index =30-40 kg/m²) and morbidly obese (group 2, body mass index >40 kg/m²). Acute Physiology and Chronic Health Evaluation II scores were not significantly different between the 2 groups. Morbidly obese patients (group 2) had higher rates of mortality and nursing home admission. They also showed higher rates of intensive care unit complications including sepsis, nosocomial pneumonia, acute respiratory distress syndrome, catheter infection, tracheostomy, and acute renal failure. Their median length of mechanical ventilation was longer (2 days, range 2-12 vs 9 days, range 1-37, P = .009). In a logistic regression analysis, morbid obesity remained a significant predictor of death or disposition to nursing home even after controlling for age ( P = .019, odds ratio = 7.60, 95% confidence interval = 1.39-41.6). Morbidly obese patients (body mass index >40 kg/m²) admitted to intensive care units have higher rates of mortality, nursing home admission, and intensive care unit complications and have longer stays in the intensive care unit and time on mechanical ventilation.