Obesity is commonly considered a surgical risk factor, but the degree of risk has been imprecisely quantified. There is little evidence that excessive body weight in itself should contraindicate general surgery. However, obesity is often associated with abnormal cardiorespiratory function, metabolic function, and hemostasis, which may predispose to morbidity and mortality after surgery. We review pertinent data and offer guidelines to minimize the risks of surgery in obese patients.