Background: Infantile hypertrophic pyloric stenosis is one of the most frequently treated surgical conditions in pediatrics and characterized by muscular hypertrophy of the pyloric sphincter, causing obstruction of the gastric out let and projectile vomiting in the new born. Aim of the study: Was to assess mothers' knowledge and practices regarding post-operative of infants with pyloromyotomy. Research design: A descriptive study was used to conduct the present study. Setting: This study was conducted in Intermediated surgical ICU Department of Benha Specialized Pediatric Hospital at  Benha city. Sample: A purposive sample of mothers who accompanied their infants diagnosed with pyloric stenosis and attended the previously mentioned setting for six months. Tools of data collection: Two tools were used to collect the required data. Tool I: A structured interviewingquestionnaire sheet, consisted of two parts: Part one; Personal characteristics of study subject. Part two; Mothers knowledge assessment sheet. Tool II: Mothers' reported  practices checklists to assess mother practice to ward post operative care of infant with pyloromyotomy. Results: The majority (80.0%) of studied mothers had poor knowledge about pyloric stenosis and pyloromyotomy operation. More than three- quarters (76.7%) of studied mothers had unsatisfactory level reported practices regarding postoperative care of infants with pyloromyotomy. Conclusion: There was highly significant correlation between mothers knowledge and their practice. Recommendations: Designing and implementing educational programs for mothers of infants  with pyloric stenosisto support them emotionally and to minimize their stress regarding pyloromyotomy.