Serous microcystic adenoma of the pancreas is an uncommon tumor in adults, and reported in pediatric patients only a handful of times. The authors present a case of a 6 month patient with incidental finding of a large cystic mass on the tail of the pancreas during an operation for Hirschsprung's disease. Final pathology was consistent with serous microcystic adenoma. This is the second case report describing this lesion in an infant, and the first time it has been associated with Hirschsprung's disease.