The present study included the examination of 100 quarter milk samples from mastitic udder. Thirty-eight (38%) Escherichia coli isolates were recovered. Most isolated strains showed typical morphological and biochemical reaction of Escherichia Antigenic studies of Escherichia coil revealed 10 "0" different serogroup of Escherichia coil. The serogroups were 06 (12 strains), untyped. 027 (8 strais), 086, 0148, 0152, 0159, 0164, 0167 (2 streins each), 0128 (one strain and 3 strains untyped. In vitro, antibiogram showed that the majority of isolated strains of Escherichia coli were sensitive to ampicillin, cefadroxil, cefataxime, chtoramphenicol, gentamicin, neomycin and nitrofurantoin, but all strains were resistant to amoxicilfin, duracef, lincomycin and oxytetracyclin.