OBJECTIVE The purpose of this paper is to discuss lethal midline granuloma (LMG)-nasal natural killer (NK) T-cell lymphoma (LMG-NTL). METHODS Literature review. RESULTS LMG is a rare entity that usually arises in the nasal cavity, exhibits a male preponderance, and has a wide age range. The majority of LMGs are LMG-NTLs. The optimal treatment of LMG-NTL is unclear and is most likely moderate-dose radiotherapy. The prognosis for patients with LMG-NTL is significantly worse than for patients with other types of head and neck non-Hodgkin lymphomas (NHL). The 5-year survival rate is approximately 20% but may be higher, depending on whether patients with less aggressive forms of NHL are included. Initial local-regional disease progression is the predominant pattern of treatment failure. Late failures after 5 years are uncommon. CONCLUSIONS LMG-NTL is a rare nasal NK/T-cell lymphoma that can be difficult to distinguish from other benign and malignant entities. Its clinical course, however, is extremely aggressive. The patterns of failure suggest a role for more aggressive local-regional treatment, as well as more effective chemotherapy.