Mumps, Measles and Rubella (MMR) vaccine has been marred by a lot of controversies since its inception. Acute pancreatitis is an uncommon condition in children and has been rarely reported following immunization. We report a toddler who developed acute pancreatitis and pancreatic pseudocyst following MMR vaccination. After ruling out other common causes, the chronology suggested the vaccine to be the possible etiology of pancreatitis. Though the exact mechanism of injury is not known, various possible mechanisms of vaccine related pancreatitis is postulated with autoimmunity being the most accepted. The report highlights a rare yet life-threatening complication following MMR vaccination which should alert the fellow Pediatricians as many of them may go un-noticed.