We present herein the rare case of a 44-year-old man found to have acute pancreatitis due to afferent limb obstruction caused by internal herniation, twelve years after Billroth II gastrectomy. The patient complained of nausea, vomiting, and epigastric pain in acute onset. Physical examination, laboratory studies and computed tomography imaging revealed acute pancreatitis and peritonitis. The patient had been operated on urgently and afferent limb herniation was observed between the afferent loop's meso and duodenum. The herniated segment was incarcerated and the proximal segment of the afferent limb and duodenum were markedly dilated. Microperforations were also observed in the dilated proximal afferent limb. The herniated segment of the bowel was released and longitudinal plication and serosal patching procedure were performed on the afferent limb. The patient recovered after fifteen days and remained free of acute pancreatitis for two years.