Background: Primary pancreatic lymphoma is really rare and comprising about 0.2-4.9% of all pancreatic malignancies. The diagnosis of this lymphoma is very difficult because the clinical symptoms and signs resemble those of pancreatic adenocarcinoma. Case presentation: A 30-year old man was admitted to the hospital with the complaint of left upper abdominal pain. Because of his splenomegaly and pancytopenia he was candidate for splenectomy but during operation a large mass was found in the pancreas and biopsy was taken from it. Pathology reported lymphoblastic lymphoma of pancreas.Conclusion: It is important to differentiate between primary lymphoma and the adenocarcinoma of the pancreas as prognosis and treatment of them differ significantly. Primary pancreatic lymphoma should be considered in differential diagnosis of pancreatic tumors and an attempt to obtain tissue diagnosis is always necessary before radical surgery, especially in young patients.