The current study was established to determine the prevalence of Escherichia coli F5 (K99) in calves introduced to slaughtering in Mosul city abattoir. Diagnosis depend on Sandwich Elisa test (SET) for detection of Escherichia coli antigens. Forty eight fecal samples were collected from calves suffering from diarrhea to detect the presence of pathogenic E.coli F5K99 antigens. The Results revealed 4 (8.33%) samples were positive for the presence of E.coli F5 (K99) antigens while 44 (91.66%) samples were negative to these antigens. Therefore we can applied Elisa technique in ante-mortem inspection at abattoir to detect the presence of pathogenic bacteria antigen including E.coli F5 (K99) which may be transmitted through the meat to avoid outbreaks.