As the buffaloe oedematous skin disease (OSD) became an endemic disease in Egypt, the present investigation objected to approach the subject in a localized district as a field study. Through a village clinic, 44 buffaloe cows suffering from OSD were included in the study. The disease was observed in two clinical forms, oedematous (95.5 %) and nodular (4.5 %), where ulcerative form was not recorded. Anterior parts of the body were mostly affected (79.5 %). Corynebacterium pseudotuberculosis was the causative agent of the disease. It was isolated from
 aspirated exudates as single infection from 32 (80.0%) and as mixed infection with Staphylococcus epidermidis from 3 (7.5 %). Twenty four (68.6 %) of these isolates showed nitrate reduction positive reactions (serotype I), while the other 11 strains  
(31.4 %) were nitrate reduction negative (serotype II). Both serotypes were recovered from adult Hippobosca equina flies. Strains of serotype I were isolated from either pupae or laboratory developed fly.
          The present study proved the sole role of H.equina fly in disease transmission. C.pseudotuberculosis was isolated from external body surface, internal body content of the fly, pupae and the second generation. Failure of its isolation from blood sucking lice confirmed that the endosymbiotic nature of C.pseudotuberculosis was limited to H.equina fly.
          Antibiogram of the isolated bacteria revealed their sensitivity 100 % for Tobrarmycin, Gentamycin and Ciprofluxacin followed by Oxytetracycline (84 %). All bacterial isolates showed resistance against Penicillin, Ampicillin and Cloxacillin. Treatment regimen basing on antibiotic, antihistaminic administration and ectoparasitic eradication achieved recovery rate of 97.72 %.