Chronic suppurative otitis media is high ratio disease in ENT field and more common than any other ear diseases. In 19th century various operative methods were introduced, and recently treatment was improved and complications were decreased by new antibiotics. In 20th century operation microscope was developed and tympanoplasty was introduced for not only cessation of middle ear discharge but also improvement of hearing by many authors. But still middle ear surgery has many problems to solve and pathologic study of chronic otitis media is necessary to improve the treatment and diagnosis of chronic otitis media. 679 cases of chronic suppurative otitis media who had taken middle ear surgery at Dept. of Otolaryngology, Han Yang University Hospital during past 7 years (from Jan. 1973 to Dec. 1979) were evaluated and report the result about age, sex incidence, involved site, duration of disease, mastoid X-ray finding, preoperative tympanic membrane state, ossicular condition, operative findings in tympanic cavity and mastoid cavity and complications with review of literature. Following results were obtained: 1) Male patients (410 cases) were more than female patients (269 cases) and its ratio was 1.52 : 1. 2) Age distribution showed predilection for 3rd decade with 300 cases (44.2%), and 2nd decade with 189 cases (27.8%), 4th decade with 146 cases (21.5%) were following. 3) In the site of diseased ear, 336 cases were in left (49.5%) and 343 cases were in right (50.5%). There was no difference in site of diseased ear. 4) The duration of disease was most prevalent in 6-10 years with 332 cases (34.3%), and 11-15 years with 132 cases (19.4%), 16-20 years with 114 cases (16.8%), below 5 years with 109 cases (16.1%) and over 20 years with 91 cases (13.4%) were following. 5) Preoperative tympanic membrane state showed total perforation was 319 cases (47.1%), large perforation 159 cases (23.4%), small or moderate sized central perforation 110 cases (16.2%), and attic perforation 41 cases (6.0%) were following. 6) In temporal bone X-ray findings, sclerotic type was most prevalent with 443 cases (65.2%), sclerotic type with cholesteatoma or bony destruction 174 cases (25.6%) and pneumatic or diploic type 62 cases (9.2%) were following. 7) Ossicular conditions were as following: destruction of ossicle with 426 cases (62.7%), and intact ossicular chain with 253 cases (37.3%) in the 679 cases. In the group of ossicular destruction total absence of ossicle was 136 cases (31.9%), and combined malleus and incus destruction 112 cases (26.3%), malleus single destruction 74 cases (17.4%), malleus, incus and stapes destruction 55 cases (12.9%) and incus single destruction 35 cases (8.2%) were following. 8) Operative findings during operation showed as follows: 232 cases with granulation tissue (34.2%), 154 cases with granulation tissue and cholesteatoma (22.7%), 152 cases with normal or slight inflammation of middle ear mucosa without granulation tissue or cholesteatoma (22.4%) and 106 cases with cholesteatoma (15.6%) in the 679 cases. 9) Complications were observed in 64 cases (9.4%), and among them 51 cases (79.7%) were found in cholesteatoma group and 13 cases (20.3%) in non-cholesteatoma group. Subperiosteal abscess (30 cases), facial palsy (14 cases), otogenic meningitis (8 cases), labyrinthine fistula (8 cases), lateral sinus thrombophlebitis (3 cases) and subdural abscess (1 case) were seen in order of frequency.