Mediastinal extention of a pancreatic pseudocyst is a rare event, Only 30 cases have been previously reportedin the literature. In most cases the pseudocyst is located in the posterior mediastinum, with entry to the mediastinum via sortic or esophageal hiatus. In the appropriate clinical settings, plain film and contrast examination of UGI may suggest diagnosis. White ultrasound may identify supradiaphragmatic extension of fluid,computed tomography is better to demonstrate the nature and extent of a mediastinal pancreatic pseudocyst. Here weare reporting a case of pancreatic pseudocyst extended to posterior mediastinum with review of literatures.