Background: Irrational breast feeding mothers' use of antibiotics is a key reason for increasing and spreading of antibiotic resistance among their infants. Aim: to evaluate the effect of an educational intervention on knowledge, practices and attitudes of mothers with breast feeding infants regarding antibiotic use and resistance on their infants. Subjects &method: A quasi-experimental research design was utilized in the present study. A convenience sampling of 60 breast feeding mothers and their infants was included in this study at Tanta City Maternal and Child Health Centers (Pottors, Embaby and Segar centers). Tools: Three tools were used, Tool I: Mothers' knowledge regarding antibiotic use and resistance questionnaire which consisted of three parts. Part 1: breast feeding mothers' characteristics, Part 2: socio-demographic characteristics of the infants and Part 3: mothers' knowledge about antibiotic use and resistance. Tool II: Breast feeding mothers' reported practices regarding antibiotic use and resistance. Tool III: Breast feeding mothers' attitudes regarding antibiotic use and resistance. Results: all studied mothers had low scores of knowledge, majority of them had unsatisfactory reported practices and negative attitudes before the educational intervention implementation, while mothers' knowledge, practices and attitudes were improved immediately and after two months from the educational intervention implementation. Conclusion: there was a significant improvement of mothers' knowledge, practices and attitudes regarding antibiotic use & resistance after the educational intervention implementation. Recommendations: Health educational programs for breast feeding mothers should be conducted periodically and regularly regarding antibiotic use and occurrence of antibiotic resistance among their infants.