Neuroendocrine tumors are rare neoplasms of the pancreas, representing 0.5% of all pancreatic tumors. Approximately, one-third of neuroendocrine tumors are hormonally inactive and called non-functioning neuroendocrine tumors. As these tumors remain clinically silent in their course of growth, they may attain great sizes without causing apparent clinical findings and commonly present in advanced stage. We report three cases of non-functioning neuroendocrine tumors with large sizes and discuss the radiological findings. (C) 2002 Elsevier Science Ltd. All rights reserved.