목적: The aim of study is to evaluate the demineralized bone matrix as a graft material for mastoid obliteration in canal wall up (CWU) mastoidectomy. 방법:This is a prospective study of patients who underwent CWU mastoidectomy with DBM obliteration. Total 13 patients were included, and in these cases, the mastoid obliteration was performed to avoid canal wall down mastoidectomy and prevent postoperative retraction. The early and late complications were evaluated. The early complications included infection and inner ear damage. Late complications included postoperative retraction/adhesion and hearing result 결과:Mean age of patients were 52.5 years and mean follow-up periods were 24 months (minimum 6months). Among early comlications, there is no postauricular wound infection in any patient. There was no symptoms and signs related with inner ear damage such as dizziness, bone conduction hearing aggravation. Postoperatively, dry ear was achieved in 12 patients (92%) within 6 weeks, but 1 patient suffered from myringitis with otorrhea which was controlled by otic drop. Among late complications, only 1 patients showed recurred attic retraction on TM without cholesteatoma. The average preoperative air conduction hearing level was 54.6dB significantly improved to postoperative values of 39.2dB (p=0.004 paired T-test). The average preoperative bone conduction hearing level was 30.6 15.1 dB (mean SD), significantly improved to postoperative values of 23.3 15.1 dB (p=0.001 paired T-test) 결론:Our study demonstrated that DBM was safe and alternative material for mastoid cavity obliteration. There was no risk of infection and inner ear damage. Postoperative retraction pocket and cholesteatoma could be prevented, while preserving the canal wall. The improvement in hearing was also achieved. Canal wall up mastoidectomy with mastoid obliteration using DBM could be safely used as an alternative of canal wall down mastoidectomy.