NK/T cell lymphoma is a rare type of non-Hodgkin's lymphomas. It has the histological features of angiocentric lymphoma characterized by prominent angio-invasion by tumor cells, and commonly presents in nasal and paranasal structures. Non-nasal from of NK/T cell lymphoma involves skin, gastrointestinal tract, or liver. With conventional chemotherapy and/or radiotherapy, NK/T cell lymphoma shows poor response rate and seldom results in long term survival. Especially, non-nasal form has more aggressive clinical manifestations and grave outcome than nasal form. We report a case of NK/T cell lymphoma presenting with small bowel perforation and malignant pleural effusion due to lymphoma infiltration, transplanted with allogeneic peripheral blood stem cells from HLA identical sibling donor after fludarabine-based nonmyeloablative chemotherapy. After transplantation, the patient achieved an enduring tri-lineage hematological complete response without any evidence of relapse for 10 months.