Serous cystadenocarcinoma of the pancreas is a rare entity. We report on a primary tumor of the pancreas in a 74-year-old male. Computerized tomography showed an abdominal mass within pancreatic head, portal vein infiltration and absence of metastatic lesions. Patient underwent Whipple's procedure and portal vein thrombectomy. Pathologic examinations of the specimen showed it to be serous cystadenocarcinoma. To the knowledge of the authors, serous cystic neoplasms of the pancreas have been uniformly benign in biologic behaviour. However, serous cystadenocarcinoma of the pancreas has been reported as a new entity. The current report is the fi rst among 22 cases described to present portal vein thrombosis and might support the local malignant behaviour of this controversial class of tumours.