Non-Hodgkin's bone lymphoma is rare, accounting for only 3-4% of all primary malignant bone tumors. The femur, tibia and humerus are most frequently affected. Most lesions are located in the medul-lary cavity of the diaphysis, or in the metaphysis adjacent to the diaphysis and the majority of patients are between 20 and 40 years old. Intermittent localized pain, dull and aching, and not relieved by rest, is present in almost all patients. Classically, the lesion begins in the bone marrow as a permeative or moth-eaten lytic process. The treat-ment of choice for primary non-Hodgkin's bone lymphoma is radiation therapy and adjuvant chemotherapy. The prognosis for this tumor is better than that for the majority of other primary malignant bone tumors, and the five-year survival rate is approximately 48%. We report a case of primary non-Hodgkin's bone lymphoma in a 9-year-old boy, describing the MR and plain film imaging findings.