Data from recent surveys indicate that a staggering 34.9% of US adults are overweight. Obese adults are at in increased risk for many chronic medical conditions, and this increases the likelihood of admission to an ICU. The critically ill obese patient presents the ICU team with many unique problems. Obesity may result in significant alterations of pulmonary and cardiac function, as well as the handling of many drugs. An appreciation of these and other changes is essential in the management of the obese ICU patient. The purpose of this article is to review some of the basic concepts related to the treatment of obese patients in the ICU.