A case of primary pulmonary malignant lymphoma (PML) was evaluated by 123I-IMP scintigraphy and 201TlCl SPECT. Radiography and CT showed a so-called lobar consolidation on the chest that was difficult to differentiate from other benign conditions. However, 123I-IMP scintigraphy showed a defect corresponding to the lesion both in the early and delayed images, and 201TlCl SPECT showed a higher retention index than that of benign disorders. Both results were highly suggestive of malignancy. These scintigraphies can help differentiate PML from benign lesions and other malignant pulmonary tumors.