The primary nasal natural killer cell (NK/T cell) lymphoma is histologically characterized by angiocentricity with invasion of blood vessels and blockage of blood vessels by lymphoma cells, resulting in marked ischemic necrosis of the normal and neoplastic tissues. The cytological appearances of the neoplastic cells are highly variable and accompanied by a mixture of inflammatory cells. On immunophenotyping, the diagnostic features are surface CD3(-), cytoplasmic CD3 epsilon(+), and CD56(+). For the majority of the cases, T-cell receptor gene rearrangement is absent, confirming an NK-cell origin of the tumor cells. Clonal proliferation of Epstein-Barr virus (EBV) is usually present in the tumor cells and is a useful diagnostic marker. Patients commonly present with nasal symptoms: mass, obstruction, or bleeding. The tumor is locally invasive and may infiltrate surrounding tissues and organs, such as the orbits, nasopharynx, oropharynx, and palate. The cranial nerves are sometimes affected. The tumor may also disseminate to skin, gastrointestinal tract, and the testis at the time of progression. Occasionally, other organ sites such as the skin are involved, sparing the nose, and it is then called the non-nasal type. A high index of suspicion is required for the diagnosis of this disease. Because of the small size of the specimen and the necrotic nature of the tumor, biopsy of the nasal tissue may not be easy to interpret. Repeated biopsies are often required. The special stain for EBV in the tumor cells may also be helpful in making the correct diagnosis. Response of primary nasal T-/NK-cell lymphoma to local treatment such as radiotherapy is often not satisfactory. Combined chemotherapy and radiotherapy has been used and appears to be more effective.