A total of 66 faccal samples were collected from diarshocic calves , aged from birth up to 2 months in El-Kalioubia and Giza Governorates, Bactcrio- logical examination of faccal samples revealed that 23 sampfes were positive with an incidence rate of 34.85 %. prevalent. microorganisms with an incidence of isolation 34.85 % , followed by salmonclla spe-cics and Yersinia cntcrocplitica (13.64 % and Escherichia coli was the highly 7.58 % respectively). Seven cases of diarrhocic calves harboured mixed infection (10.6 %) while 16 cases were single infection . All isolates were subjected to scrological examination and the re-sulls showed that 3 isolates of Escherichia coli were typed by O:k serotypes including OII! (2 isolates), O119 (1 isolate) while 6 isolates were lyped by K99 antisera. Nine isolates of Salmoncl-la were typed as Salmonella typhimurium (5 tso-,lates), Salmonella dublin (3 isolates) and Salmo- nella cnicritidis (1 isolate). Five isolates of Yersi- |nia entcrocolitica were typed as O3 (3 isolates) and O9 (2 isolates) . Pathogenicity test was car: ricd oul using suckling mousc technique and the results showed that 12 isolates of Escherichia coli and all isolates of Yersinia enterocolitica were cn- crotoxigenic .