The open abdomen has become a critical component to the management of patients with life threatening intra-abdominal surgical emergencies. These span from massive hemorrhage to severe sepsis and septic shock. Leaving the abdomen open and placing a temporary abdominal closure device is often employed for a variety of reasons. For hemorrhage it can allow resuscitation, rewarming and correction of coagulopathy. With respect to infection, patients with septic shock also often have severe physiological derangements including profound acidosis or sepsis induced coagulopathy. The profound immune and inflammatory response to both the initial septic event as well as the response to the abdomen being left open are affected by the mechanism of action of the device used to cover the abdomen with the temporary abdominal closure. This talk will address the mechanisms of action of a wound vacuum and how these devices affect the abdominal cavity as well as the intestines. Furthermore, the mere presence of an open abdomen does not mandate prolonged antimicrobial agents and this talk will discuss the role and duration required for patients with an open abdomen. We will review the clinical indications for leaving the abdominal wall open at the end of a laparotomy, methods to treat it, and common complications.