Colonic fistula is a rare and potentially critical sequela of severe acute pancreatitis, which requires surgical treatment. We report two cases that were successfully treated by a colectomy for colonic fistula associated with severe acute pancreatitis. Case 1 is a 71-year-old man infected with pseudocysts owing to severe acute pancreatitis that developed into a colonic fistula as an early complication with a resulting pancreatic abscess. This patient underwent a left hemicolectomy, a transverse colostomy, and drainage of the pancreatic abscess. He has done well without recurrent disease for 35 months following surgery. Case 2 is a 58-year-old woman who had a past history of drainage during a laparotomy for a pancreatic abscess induced by endoscopic retrograde cholangiopancreatography 10 years earlier. She was admitted to our hospital with left lateral abdominal pain and low-grade fever. Abdominal magnetic resonance imaging showed a retroperitoneal abscess and fistula to the descending colon. She underwent a left hemicolectomy and drainage of the retroperitoneal abscess. She has remained symptom-free for 20 months following surgery. The colonic fistula should therefore be recognized as a late complication during long-term follow-up as well as an early sequela associated with severe acute pancreatitis.