Chronic suppurative otitis media is one of the most frequent disease in otolaryngologic field. It is important to know periodical incidence of pathogenic organisms, its sensitivity to antibiotics and relationship to type of infection for sensitivity to antibiotics and relation ship to type of infection for sensitivity to antibiotics and relationship to type of infection for better treatment and minimize serious complications of chronic suppurative otitis media. Author has performed bacteriological study of discharge from the middle ear or mastoid in 65 cases with chronic suppurative otitis media at Kyung Hee University Hospital from January 1977 to August 1978. The results obtained were as follows : 1) Among 65 cases of chronic suppurative otitis media, pathogenic organisms were isolated in 46 cases(70.8%) consisting of 44 cases of single infection and 2 cases of mixed infection, and not isolated in 19 cases(29.2%). 2) Among 48 strains of isolated organisms, proteus(20 strains) was most frequently isolated and Staphylococcus aureus(9 strains), Staphylococcus epidermidis(5 strains) were next. Pseudomonas, Streptococcus and the others were very few. 3) Proteus nd staphylococcus seemed to be more frequently isolated in younger age group. 4) Of 23 cholesteatomatous otitis media, pathogenic organisms were isolated from 21 cases(91.3%), and proteus was isolated from 11 cases(47.4%). On the other hand, of 42 non-cholesteatomatous otitis media, pathogenic organisms were isolated from 25 cases(59.5%), and proteus was isolated from 9 cases(21.4%). 5) Among 7 cases of otogenic intracranial complications, 5 cases were resulted from chronic middle ear infection with proteus. But only one case of proteus was detected in intracranial lesion. 6) Proteus was sensitive to dibekacin(100%), carbenicillin(100%), kanamycin(95%), gentamycin(95%), cephalosporin(90%), ampicillin(90%), streptomycin(85%) and resistant to tetracycline(85%). 7) Staphylococcus was sensitive to cloxacilline(100%), minocin(100%), cephalosporin(100%), lincocin(93%), erythromycin(86%), penicillin(86%) and resistant to tetracycline(72%). 8) Pseudomonas was sensitive to dibekacin(100%), sulbenicillin(80%), gentamycin(80%) and resistant to chloramphenicol, tetracycline kanamycin etc..