Duodenal stump fistula is perhaps the most feared complication after total or subtotal gastrectomy due to its high rates of morbidity and mortality. This will typically be encountered in post-operative gastric cancer patients treated with Billroth II or Roux-en-Y reconstruction. Bariatric patients with Roux-en-Y anatomy can also suffer blowouts of the duodenal stump due to back pressure from bowel obstruction. Successful management relies on rapid diagnosis, resuscitation, source control, antimicrobial therapy, and nutritional support. The patient’s condition will dictate how each of these principles should be pursued. Patients with hemodynamic instability need prompt resuscitation and expeditious operative management, sometimes with damage control techniques.