A case of a 53-year-old man with adult T-lymphoblastic lymphoma (T-LBL) in mediastinum who survived more than 33 months in our hospital was reported. LBL was more common in school-age and teenage boys than adults. The reported patient manifested progressive dyspnea. Chest CT scanning showed a huge irregular soft tissue shadow in anterior mediastinum which extended into posterior mediastinum and left chest wall. The tumor was 20 cm×15 cm×15 cm in size in left upper mediastinum and its boundaries with pericardium and left lower lung were unclear. The diagnosis of T-lymphoblastic lymphoma was confirmed by immunohistochemical staining. After surgery, he received five chemotherapy courses including Gem, CTX and VCR and biological therapies with IL-2 and IFN-α2b. About 16 months later, he complained of diplopia in the left eye without any evidence of recurrence. Blood examination which showed leukemoid reaction twice returned to normal after dehydration, hormone and thalidomide treatments. Finally, his condition became worse and died of pulmonary infection 33 months after ifrst medical service. In summary, T-LBL is a rare disease which may result in poor prognosis even if the patient has received immediate chemotherapy. Hormone and thalidomide can be applied to treat adult T-LBL.