Primary CNS lymphoma (PCNSL) is now thought to constitute 3% of all intracranial neoplasms. PCNSL occurrence in the sella turcica region is an extremely rare finding. We present a 37-year-old male with primary pituitary lymphoma treated in our department. The patient, who had had no previous illnesses, was admitted to the hospital because of bilateral blurred vision. Findings on physical examination were normal except for temporal parts of field of vision deficit. No abnormalities were found in his bilateral ocular movement, facial sensory function or motor function. His blood count and biochemical profile were normal. Basic hormonal studies revealed no symptoms of panhypopituitarism. MRI demonstrated a large intrasellar mass with supra- and parasellar extension. MRS revealed decrease in NAA/tCr proportion and increase in Cho/NAA and Cho/tCr proportions. Endoscopic surgery was performed using the transsphenoidal approach. Histopathological examination demonstrated a large B-cell lymphoma. The patient received 6 cycles of CHOP chemotherapy. He was also irradiated with 6 MV photons to the whole brain to a total dose of 40 Gy and then there was a boost to the tumour to a total dose of 50 Gy. Next he was reoperated on with the fronto-temporo-sphenoidal craniotomy approach and subtotal resection of the tumour was performed. After the treatment the visual disturbances significantly decreased. Control MRI revealed a stable remnant of the tumour. Nowadays the patient has 52 months' follow-up and he has only a stable, slight visual field deficit on the upper temporal side of the right eye.