I have analyzed a series of 793 cases of acute purulent otitis media from my private practice and from the otolaryngologic service of St. Luke's Hospital in the past three years. About 90 per cent of the hospital cases I have seen personally; in about 45 per cent of them the age was 10 years or less, making a fairly equal number of children and adults. It should be noted that St. Luke's is a general hospital, that many of the patients in the series were admitted because of other medical conditions which were complicated by otitis, and that the presence of other pathologic conditions always makes otitis more severe, more prolonged and more difficult to cure. Before proceeding to my series of 793 cases of otitis media, it may be interesting to trace the incidence of mastoidectomies for the past ten years, in an effort to discover the influence