Lethal midline granulomatosis is one of the nonhealing diseases in the otolaryngologic field except cancer and characterized by necrotizing granulomatous lesions in the upper respiratory tract or in the lower respiratory tract or both, generalized focal necrotizing vasculitis involving both arteries and veins and granulomatous glomerulitis. Also about this rare interesting disease the precise etology and the radical treatment are unknown up to now but massive steroid therapy, chemotherapy such as antimetabolites and rediotherapy, or combinations of these were known to be beneficial to this disease. Most patients die within 6 months after the onset. Author carried out the clinical study of 35 cases which were diagnosed as lethal midline granulomatosis and were treated at the Hospital of Seoul Nat. Univ., Hospital of Chunnam Univ., National Medical Center, Chunju Presbyterian Hospital from Mar. 1962 to Mar. 1974. Results are as follow ; 1) In 21 cases (60%) the age distribution generally shows a peak in the 30 to 50 year old group. Male were involved approximately 2.2 times more frequently than females. 2) In 26 cases (74.3%) prodromal period was within 6 months and in the expired 11 cases among the 35 cases the average survival period was 7.4 months after the onset and the (average) active period was 2.5 months. 3) Most frequent early symptoms were nasal obstruction, fever with chillness, continuous purulent nasal discharge, sore throat, vesicles and ulceration on the mucosa and headache. 4) Radiologic findings of the paranasal sinuses were clouding 13 cases (39.4%), hypertrophy of the mucosa and the periosteum 11 cases (33.3%), bony destruction 6 cases (18.2%) and mass density 3 cases (9.1%). 5). E.S.R. was increased in 17 cases (48.6%) and the average r-globulin in the serum protein was 30.75%. Arteritis and periarteritis were seen in 17.8%. 6) Steroid, antimetabolites and radiotherapy or combinations of these were effect and the affected regions seem to palliate or arrest the process. Autohematherapy was not satisfactory but seems to be beneficial.