From January 1970 through December 1984, 15 patients with sinonasal Non-Hodgkin's lymphoma combined to the head and neck were treated by external irradiation. 13 patients were stage IE and 2 were stage IIE by Ann Arbor Classification. However, when using TNM system, 7 were locally advanced T3, T4 lesions. All patients had follow up from 3.7 to 16 years with the median follow-up of 8.5 years. The overall actuarial 5-year survival rates were 25%, 28% for IE and 0% for IIE. Total tumor dose varied from 40 to 68 Gy. 100% complete response with a total tumor dose of more than 55 Gy and 73% complete response with less than 55 Gy. When the disease was staged using the TNM (AJC) system, the five-year disease free survival for T1 and T2 patients was 50% as compared with 14% for T3 and T4. Failure rate by stage was 33% (2/6) for T1 and T2, 86% (6/7) for T3 and T4, and 100% (2/2) for IIE. The results suggest that 1. Higher CR could be obtained with a total tumor dose of more than 55 Gy. 2. Use of TNM staging system is as important as Ann arbor in management of sinonasal NHL. 3. The addition of combination chemotherapy should be considered for T3, T4 and IIE the sinonasal Non-Hodgkin's lymphoma although the disease is limited to head and neck.