A 49 years-old man presented with dry cough, low grade fever, and abnormal shadow on a chest X-ray. He had suffered from follicular lymphoma of the liver 5 years previously. He received irradiation therapy in combination with chemotherapy for approximately three years and had been in complete remission. Physical and radiological examination revealed pleural effusion and softly dense masses in the right lung. The laboratory data were within normal limits. He was diagnosed as having lymphomatoid granulomatosis (LYG) by open lung biopsy. The lung lesion was mainly infiltrated with T cells. The patient received prednisolone and the lung lesions disappeared. However, when a lung mass was noted two months later, he started to receive combination chemotherapy consisting of cyclophosphamide, adriamycin, vincristine, and prednisolone every three months. He has not shown relapse of LYG so far. To investigate the association between the preceding follicular lymphoma and subsequent LYG at this time, DNA analysis using the PCR technique was carried out. The LYG lesion did not show a rearranged band for the JH probe, while the paraffin-embedded specimen of the preceding follicular lymphoma had shown rearranged band for the JH band. Southern blot analysis of the LYG lesion, showed no rearrangement for TCR beta, gamma or JH probe. These findings indicate that the LYG was different from the preceding follicular lymphoma in terms of origin. LYG is considered to be induced in the immunosuppressive state due to lymphoma.