Objective To assess the efectiveness of platelet rich plasma (PRP) in promoting epithelialization and healing of mastoid cavity after canal wall down mastoidectomy. Subjects and methods This study was applied on 20 patients with chronic sappurative otitis media who were operated by canal wall down mastoidectomy and PRP was added along sidewalls of the mastoid cavity. The patients were followed up clinically by otoscopic examination every 2 weeks for 4 months for detection of complete healing, otorrea or crustations. Results During the follow up period, all cases show early epithelialization and good healing of the mastoid cavity with no infection; wound dehiscence, granulation tissue formation, otorrea; or debris accumulation. Conclusion Coating the bare bony wall of the opened mastoid cavity after CWD mastoidectomy by PRP is a novel and efective method promoting healing and decreasing mastoid cavity problems.