A 46-year-old man with a long-standing history of Crohn's disease who was treated with multiple therapies over a period of 9 years presented with oral lesions which on biopsy demonstrated peripheral T-cell lymphoma. Initially, the development of T-cell lymphoma was presumed to be secondary to prolonged immunosuppression but it did not respond to withholding immunosuppressive therapy. On treatment with CHOP (cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone) chemotherapy, complete remission was achieved. Although development of malignancies in the immune-suppressed patient with Crohn's disease has been previously described but we present a rare case of T-cell lymphoma in a similar patient, which has not been reported before.