Pancreata with cancer also frequently have intraductal proliferative lesions, suggesting an association between pancreatic cancer and these lesions. We present three cases in which atypical papillary hyperplasia of the pancreas was documented 17 months to 10 years before the development of an infiltrating adenocarcinoma of the pancreas. The first patient was a 70-year-old woman who underwent pancreaticoduodenectomy for adenocarcinoma of the pancreas. Atypical papillary duct hyperplasia extended to the pancreatic neck margin of resection, but the margin was negative for infiltrating carcinoma. Nine years later, an infiltrating adenocarcinoma developed in the remaining pancreas. The second patient was a 58-year-old man who underwent distal pancreatectomy for chronic pancreatitis with pseudocyst. Histologic examination showed chronic pancreatitis and multiple foci of atypical papillary duct hyperplasia. Ten years later, the patient underwent a Whipple procedure for infiltrating adenocarcinoma of the pancreas. The third patient was a 46-year-old woman with recurrent pancreatitis who underwent a Whipple procedure. Histologic examination showed atypical papillary duct hyperplasia and chronic pancreatitis but no infiltrating carcinoma. At the time of surgery, the tail of the pancreas was grossly and radiographically normal. Seventeen months later, a malignant pleural effusion developed, and postmortem examination showed infiltrating adenocarcinoma in the tail of the pancreas. In the cases presented, atypical papillary hyperplasia was documented 17 months, 9 years, and 10 years before the development of infiltrating adenocarcinoma of the pancreas, supporting the concept that there is a progression from intraductal hyperplasia to infiltrating carcinoma of the pancreas, just as there is a progression from adenoma to infiltrating carcinoma in the colorectum. Based on evidence that these intraductal lesions are precursor lesions to infiltrating adenocarcinoma of the pancreas, we suggest that the term "hyperplasia" be replaced by the more specific term "pancreatic intraepithelial neoplasia."