Introduction: This research was conducted for the purpose of evaluating the antidiarrheal effect of Capparis spinosa fruits methanolic extract and ciprofloxacin against resistant E. Coli. O157:H7. Objective: This research aimed to know the antidiarrheal effect of Capparis spinosa fruits extract against resistant E. Coli. O157:H7. Patients and methods: The extract dose that used in this study was 400 mg/kg of rat weight and 7.14 mg/kg of ciprofloxacin twice daily for seven days. A one ml containing concentration of 1.0 × 10⁹cfu/ml of the activated cells from E. Coli. O157:H7 was obtained to be administrated orally to experimental animals. Results: This extract showed antidiarrheal activity leading to return of electrolytes to nearly normal value and caused reduction in the number of stools and bacterial count. The results of this study suggest that using C. Spinosa fruit extract may have the perfect to be choice in treatment of diarrhea a result of E. coli O157:H7. The findings indicated the alcoholic C. spinosa fruit extract contained some biologically active compounds that may be effective against diarrhea. This finding may explain why the substance has traditionally been used to treat gastrointestinal diseases. Conclusion: There was evidence that the methanolic extract of C. spinosa fruits had antidiarrheal activity against E. coli O157:H7.