Several chemotherapeutic agents are known to develop pulmonary toxicities in cancer patients, although the frequency of incidence varies. Cyclophosphamide is a commonly encountered agent that is toxic to the lung. Additionally, granulocyte colony-stimulating factor (G-CSF) being used for the recovery from neutropenia can exacerbate lung injury. However, most of the patients reported previously that the drug-induced interstitial pneumonitis were developed after three to four cycles of chemotherapy. Hereby, we report a case of peripheral T cell lymphoma which rapidly developed a fatal interstitial pneumonitis after the first cycle of combined chemotherapy with cyclophosphamide, adriamycin, vincristine, prednisolone, and etoposide and the patient had also treated with G-CSF during neutropenic period.