Background and objective: The aim of this study was to evaluate bioactive glass as an ideal material for the purpose of mastoid cavity elimination after mastoid surgery to avoid mastoid cavity problems. Materials and methods: In 20 patients diagnosed as cholesteatoma or chronic unsafe ear, we used different surgical techniques according to pathology and situation during surgical exploration, basically adhering to standard principles of eradicating disease in chronic unsafe ear. After performing the canal wall down (CWD) or the canal wall up (CWU) technique, mastoidectomy was followed by obliteration of mastoid cavity by particulate form Bioglass®. Cases were divided according to operative procedures, type of reconstruction and material used into 3 groups A- Canal wall up mastoidectomy followed by obliteration of mastoid cavity by particulate form Bioglass®. B- Canal wall down mastoidectomy followed by reconstruction of posterior meatal wall and obliteration of mastoid cavity by particulate form Bioglass®. C- Canal wall down mastoidectomy followed by reconstruction of posterior meatal wall by conchal cartilage and obliteration of mastoid cavity by Bioglass®. Results:  Bioactiveglass paste is very effective for mastoid obliteration in the three groups with good integration to the surrounding tissues either connective tissue, bone, meninges or lateral dural sinus without any adverse reaction on the dura even with contact to Bioglass®. Infection was seen in 2 cases (10%), however was readily controlled by topical application of antibiotics daily for one week. In both cases no extrusion of the material occurred. Conclusion: The successful formation of bone with elimination of mastoid cavity problems proved that using Bioglass is appropriate for performing clinical mastoid obliteration.