The authors made a study on the bacteriological identification about unidentified strains which were roughly screened by local health center, which an epidemic diarrhea was outbreak at Ham Yang Gun, Kyeongsang-Namdo in July 1971. And the authors made an attempt to bacteriological Identification, serotyping with slide agglutination, and determination of the susceptibility of identified strains to various chemotherapeutic agents. The results Were obtained as follows: 1. The isolated strains identified Shigella flexneri type 2b(2 strains) and Salmonella paratyphi B(4 strains). 2. Sensitivity test using with three concentrations chemotherapeutic agents(Paper disk used; Eiken chemical Co., Tokyo, Japan): (1) Shigella flexneri type 2b isolated strains were sensitive to kanamycin, colistin(100%) and penicllin(50%) respectively, but resistant to erythromycin, oleandomycin, leucomycin, chloramphenicol, tetracycline, dihydrostreptomycin and sulfadimethoxin(100%) respectively. (2) Salmonella paratyphi B isolated strains were sensitive to chloramphenicol, tetracycline, dihydrostreptomycin, kanamycin, sulfadimethoxine(100%) and colistin(50%) respectively, but resistant to penicillin, erythromycin, oleandomycin and leucomycin(100%) respectively. 3. Sensitivity test using with multodisk urinary code(Paper disk used; Oxoid, London): (1) Shigella flexneri type 2b isolated strains were sensitive to Bactrim, ampicillin, nitrofurantoin, nalidixic add and gentamicin(100%) respectively, but resistant to chloramhpenicol, tetracycline, sulfadiazine and Fanasil(100%) respectively. (2) Salmonell paratyphi B isolated strains were sensitive to Bactrim, chloramphenicol, ampicillin, nitrofurantoin, tetracycline, nalidixic acid, gentamicin(100%) and sulfadiazine(50%) respectively, but resistant to Fanasil(100%) and sulfadiazine(50%) respectively.