Variation in the quality of healing in mastoid cavities has never been clearly understood. It is the author's contention that the factor responsible for the wide variation in healing, even though all chronic disease has been removed, is buried mucosa which leads to cystic formation. Over the past 20 years the author has followed the principle of removing all mucosa from the mastoid segment and has been rewarded with dry ears routinely in open cavity surgery. For the past 12 years he has removed cholesteatoma through tympanoplasty and modified radical mastoidectomy. These cases, also, have been consistently free of cavity problems. In the late 50s and early 60s closed cavity operations were tried in radical mastoidectomy, fenestration and tympanoplasty with mastoidectomy. Postoperative healing difficulties were encountered then that are similar to those being reported now with intact canal wall operation. No conclusions are drawn in the controversy between open and closed cavity techniques. The observation may be made, nevertheless, that the problems of closed cavity operations have not been solved. It is the thesis of this paper that the main objection to open cavity operations, ie, poor quality of healing, has been resolved.