Obesity has emerged as one of the most complex and debilitating diseases affecting the world's population. It is estimated that more than two thirds of Americans are overweight and more than 20% are obese. This disease is associated with many morbid conditions, including hypertension, coronary artery disease, hypoventilation, sleep apnea syndrome, diabetes mellitus, and an increased incidence of certain malignancies. Medical interventions for achieving and maintaining significant weight loss have generally failed, leaving surgery as the only effective treatment for durable weight loss. A number of surgical options are available today and can be grouped into two categories based on the mechanism of how the weight loss is achieved. Restrictive procedures include vertical banded gastroplasty (VBG), adjustable gastric banding (AGB), and Roux-en-Y gastric bypass (RYGB), although the latter does have some altered absorption as well. Largely malabsorptive procedures include biliopancreatic diversion (BPD) and biliopancreatic diversion with duodenal switch (BPD-DS). Whereas VBG has largely fallen out of favor due to inadequate long-term weight loss, the other procedures have proven successful in achieving and maintaining adequate weight loss. In addition, each has proven successful in reversing or ameliorating many of the comorbidities associated with obesity. RYGB is the most common procedure performed in the United States and is considered the gold standard. It has the best short- and long-term results for safety, efficacy, and durability, and it has been proven to be superior in results to those for AGB. In experienced hands, this technically challenging procedure can now be performed laparoscopically. This method has the same weight loss and health benefits as the open procedure while achieving all the added benefits of a minimally invasive approach. Long-term data seem to support the malabsorptive procedures as most effective in the superobese. All the procedures require compliance and long-term nutritional follow-up.