In recent years, there has been so many pathogenic organisms which have been increased the resistance to antibiotics because of inadequate treatment of antibiotics for chronic suppurative otitis media. Therefore it is important to know periodically varieties of pathogenic organisms and its sensitivity to give better treatment and minimize serious complications of chronic suppurative otitis media. The author studied bacteriologically on discharge obtained from the middle ear and mastoid in 133 chronic suppurative otitis media at Busan National University from 1966 to 1973, and the results obtained were as follows : 1) Variety of pathogenic organisms were numerous, among which staphylococcus, coliform bacilli and pseudomonas were most often cultured from discharge of the middle ear and mastoid cavity. 2) Mixed infected organisms in discharge of the middle ear were more often cultured than in discharge of the mastoid cavity. There was coliform bacilli most often detected among mixed infected organisms. 3) The same pathogenic organisms cultured from discharge of both the middle ear and mastoid cavity were found in only about 30 percent. 4) There were relatively often cultured mixed infected organism from putrid odorous discharge in the middle ear, associated with more often coliform bacilli. On the other hand, there was often less cultured mixed infected organisms from odorless discharge. 5) There was no any relation of particular organisms to the presence of cholesteatoma otitis media. But staphylococcus was most often isolated from discharge in the middle ear and mastoid in otogenic intracranial complications. 6) Staphylococcus aureus was generally sensitive to neomycin, kanamycin and gentamicin. Staphylococcus albus to albamycin, kanamycin and bactrim. Streptococcus to kanamycin, streptomycin, neomycin and gentamicin. Pseudomonas and proteus were most sensitive to gentamicin. However staphylococcus aureus was resistant to sulfadiazine, penbritin and ampicillin. Staphylococcus albus to sulfadiazine, leukomycin and ampicillin. Streptococcus to albamycin, leukomycin and terramycin. Coliform bacilli to ampicillin, penicillin and leukomycin. Pseudomonas and proteus were very resistant to other antibiotics except gentamicin.