We have performed 85 cases microsurgery of middle ear and mastoid to the patients of chronic ear disease during the period of Aug, 1980 to May, 1982. In this investigation, the author analyzed 87 cases of chronic otitis media Clinicostatically. And the following results were obtained : 1) The total cases of operation were 87, 68 cases (78.1%) were male and 19 cases (21.9%) were female. 2) Age distribution shows 57 cases (65.5%) in 3rd decades, 12 cases (13.8%) in 4th decade. 3) Site incidence of operated cases ; Rt side were 46 cases (52.9%), Lt side were 41 cases (47.1%). 4) Characters of Otorrhea ; Dry states were 34 cases (39.1%), Seruminous states were 18 cases (20.7%), Purulent states were 35 cases (40.2%). 5) Conditions of eustachian tube function ; Good were 71 cases (81.6%), fair were 6 cases (6.9%), poor were 10 cases (11.5%). 6) Sites of drum perforation ; 52 cases (59.8%) in central perforation, 9 cases (10.3%) in total perforation, 16 cases (18.3%) in attic, 7 cases (8.0%) in marginal perforation, 3 cases (3.4%) in adhesion. 7) X-ray findings of temporal bone were 65 cases (74.7%) in sclerotic, 20 cases (23.0%) in diploic, 2 cases (2.3%) in pneumatic. 8) Types of preoperative hearing loss were 35 cases (40.2%) in conductive, 31 cases (35.6%) within normal limit, 12 cases (13.8%) in sensorineural. 9) Degrees of preoperative hearing loss were 31 cases (35.6%) in normal, 31 cases (35.6%) in mild, 8 cases (9.2%) in moderate, 7 cases (8.1%) were moderate severe, 6 cases (6.9%) were severe, 3 cases (3.5%) in profound. 10) Conditions of middle ear mucosa were 47 cases (54.0%) in diseased, 24 cases (27.6%) in intact, 16 cases (18.4%) in squamous. 11) Conditions of ossicles : 61 cases (70.1%) were intact, 24 cases (27.6%) were missing, 2 cases (2.3%) were fixed. 12) Extents of cholestatoma were 12 cases in attic -antrum-middle ear, 7 cases (33.3%) in attic antrum, 1 case (4.8%) in attic and 1 case (4.8%) in attic -middle ear. 13) The routes of approach were 47 cases (54.0%) in endaural, 39 cases (44.8%) in postauricular, 1 case (1.2%) in transmeatal. 14) Types of anesthesia were 78 cases (89.7%) by general anesthesia, 9 cases (10.3%) by local anesthesia. 15) Graft materials of the drum were temporal fascia 86 cases (98.9%) 16) Incidences of surgical accident were 4 cases (4.6%) in facial canal exposure, 9 cases (10.4%) in dural exposure, 1 case in horizontal canal fistula, 1 case in oval window fistula, 2 cases lateral sinus exposure. 17) Post operative complications were 3 cases (3.4%) in perichondritis, 1 case (1.2%) in canal stenosis. 18) Types of operation were 45 cases (51.7%) in tympanoplasty with mastoidectomy, 19 cases (21.8%) in tympanoplasty without mastoidectomy, 10 cases (11.5%) in revision, 9 cases (10.4%) in radical mastoidectomy, 2 cases (2.3%) in myringoplasty and others.