Primary malignant lymphomas of the lung are rare and known often to be localized, solitary pulmonary lesions, in chest radiograph. Because they are highly treatable contrast to the other primary lung cancer, the distinction is important. A 35-year old man who was admitted for a solitary pulmonary nodule in the right middle lobe. Percutaneous needle aspiration disclosed diffuse, small cell lymphoma. Bone marrow biopsy showed no evidence of neoplastic lymphoid cell infiltration. There were a walnut sized mass involving right middle lobe with a small satellite nodule at 2cm distal to the right upper lobe bronchial orifice. The histopathology of the bilobectomized specimen showed diffuse, small cell, malignant, non-Hodgkin`s lymphoma. Immunologic subtype was defined as B-cell type.