Cystic lesions of the pancreas are identified with increasing frequency by modern imaging. The mucinous cystic neoplasm (MCN) is treated with resection for its malignant potential. How much preoperative evaluation is needed before undertaking operation is frequently a diagnostic dilemma. A retrospective review of 32 patients who underwent resection of a MCN between 1994 and 2007 was performed to define the preoperative evaluation and operative treatment of MCN patients. Thirty-two patients (30 women; mean age 49) had histology-proven MCN. Twenty-seven patients had symptomatic cysts (84%). Five had a history of gallstones and/or acute pancreatitis. All patients were worked up with CT and/or MRI. Endoscopic ultrasound was performed in 14 (44%) and endoscopic retrograde cholangiopancreatography in six (18%). Cytology was obtained in 13 (40%). Pathology revealed 22 benign MCNs (68%), five malignant MCNs (16%), and five MCNs with borderline pathology. Preoperative workup including CT or MRI imaging and cytology suggested MCN as the lesion in 15 patients (46%). CT features by itself predicted MCN in three patients (9%). Cytology revealed another six patients (19%) with possible MCN. In this series, preoperative workup did not identify three of five patients with MCN malignancy. A preoperative diagnosis cannot be made in most patients with MCN. Operative treatment can be based on clinical presentation and CT imaging because endoscopic ultrasound and fine needle aspiration for evaluation may be misleading. Middle-aged women with cystic lesions in the tail of the pancreas without prior gallstone or pancreatitis history most typically fit the profile of the MCN patient.