Bacteriological examination carried out on rectal swabs of mice, revealed that E. colt was the predominant organism compared with other enteric bacteria from apparently healthy mice. The percentage of isola• tion was 25.45%, whereas, in case of diseased mice, the percentage of isolation was 57.69%. Serological typing of E. cog strains isolated from diseased mice revealed that they belonged to different serogroups which included On 9. ⁰128. Ot 27. ⁰111, 085 and Om The pathogenicity test of E. soli isolates in mice proved that all of them were highly 'pathogenic. Most E. cote isolates were highly sensitive to gentamycin, kanamycin, chloramphenicol, neomycin and tobramycin. On studying the effect of sterile extract of E. coli on tissue culture, we found that 62.06% had cy­topathic effect, and for detection of enterotoxins production, the infant mice used were positive for enterotoxigenic effect.