Since 1967 we have operated on the chronic middle ear disease with operating microscope, its methods and results have been read several occasions. The whole number of the patients who received microsurgery of middle ear is 1213 cases. Among them, author analyzed 740 cases of chronic middle ear disease except cholesteatoma since March, 1967 to October, 1979. (Other group of 473 cases who was diagnosed as cholesteatoma will be reported by other). 1. The total cases of operation was 740 : 440 cases (59.5%) were male & 212 cases (45%) were female. Sex ratio was 1.5 : 1. 2. Age distribution were 292 cases (39.5%) in 3rd decade, 53 cases (7.1%) 1st decade and 5 cases (0.6%) were above 60 yrs. Old. 3. The type of operation for chronic ear disease : 452 cases (61.1%) were intact canal wall tympanoplasty with mastoidectomy, 72 cases (9.7%) were type II tympanoplasty. 4. The number of cases who received operation more than 2 time (revision) were 255 cases (34.5%), 169 cases (77.5%) were revision for ossicle reconstruction, 32 cases (14.7%) were revision for tympanoplasty. 5. The postoperative complication was : 85 cases (81%) was post op. infection, 8 cases (7%) was drum retraction, 5 cases (4.7%) was tenting, recurred cholesteatoma was 4 cases (3.8%) and loss of hearing was 3 cases (2.9%).