Cystic tumors of the pancreas are rare and can be confused with pseudocysts.We present a 50 year old woman with a huge mucinous cystadenoma of the pancreas initially diagnosed and managed with a cystojejunostomy and cyst wall biopsy. She required another laparotomy and tumor excision after histological diagnosis. Sensitivity of radiological imaging in differentiating between cystic pancreatic tumors and pseudocysts is limited. Cyst wall histology is diagnostic and biopsy of cyst wall should be done in cases with inconclusive preoperative diagnosis or questionable operative findings.