Objective: To evaluate the usefulness of homologous costal cartilage as a graft material for mastoid cavity obliteration after the canal wall down mastoidectomy.Methodology: The patients who have undergone CWD mastoidectomy with tympanoplasty type Ⅰ and mastoid obliteration with homologous costal cartilage were enrolled.Operations were performed in 6 children patients and their mothers from 2011 to 2013.Costal cartilage swere harvested from 6 patients mother and prepared for 2 weeks before transplant.After 2 weeks preparation, CWD mastoidectomy with tympanoplasty type Ⅰ was performed and mastoid obliteration was done with homologous costal cartilage.Hearing results was checked according to the hearing result report guideline in chronic otitis media surgery of Korean Otologic Society.Postoperative complications were checked in the frame works of postoperative dehiscence, persistent otorrhea, ear drum perforation and absorption of obliteration material.