This study was aimed to evaluate surgical outcome of patients undergoing obliteration of mastoid cavity with postauricular composite osteo-periosteal flap. This interventional study was carried out on 100 patients having unsafe CSOM from Nov. 2012 to Oct. 2014 who underwent canal wall down mastoidectomy with tympanoplasty and obliteration of cavity using composite osteo-periosteal flap. The primary outcome measure was control of suppuration and creation of dry, low-maintenance mastoid cavity, which was assessed using Merchant et al. grading system. At the end of 1 year follow-up, 89% patients had Grade 0 summary score while Grade 3 which was considered as failure of control of infection was not obtained in any patient during the entire follow-up period. Mastoid cavity obliteration using composite osteo-periosteal flap is an effective technique to avoid cavity problems.