Primary splenic lymphoma is a relatively infrequent disease; the diagnosis of this entity is currently made with splenectomy. In a 52-year-old female with left upper quadrant abdominal pain, ultrasound showed a normal-sized spleen with an internal hypoechoic focal lesion. Ultrasonically-guided fine-needle aspiration and tissue core biopsy of the splenic lesion showed non-Hodgkin's lymphoma (NHL). At the time of presentation there was no evidence of involvement of lymph nodes, bone marrow or any other organ. A diagnosis of primary splenic non-Hodgkin's lymphoma was made and the patient underwent laparotomy with splenectomy. Histologic examination of the spleen confirmed the diagnosis: low-grade NHL confined to the spleen. The patient is well and in complete remission seven months after diagnosis. The purpose of this paper is to report a rare occurrence of primary splenic lymphoma and to demonstrate the possibility of making this diagnosis by percutaneous guided biopsy.