ABSTRACT Background: Open heart surgery is an incision that is made through the breastbone while the child is under general anesthesia. The aim of the study was to assess mothers' care for their children with open heart surgery. Research design: A descriptive research design was utilized to conduct this study. Setting: This study was carried out at the Cardiac Outpatient Clinic in the Kaluobia Governorate, which is connected to the Bahteem Health Insurance Hospital for Specialized Surgeries. Sample: Purposive sample was used in this study. It included 150 mothers whose children had open heart surgery. Tool of data collection: one tool was used and consisted of five parts: A structured interviewing questionnaire to assess socio demographic characteristics of mothers, personal characteristics of children, medical history of children, knowledge of mothers about open heart surgery, and reported practices of mothers care for their children with open heart surgery. Results: 48.7% of the studied mothers were between the ages of 20 and fewer than 35 years old. 50% of the studied children aged 1 to less than 5 years, 63.3% of them were boys. 48% of the studied mothers had average total knowledge level about open heart surgery. 55.3% of studied mothers had satisfactory total reported practices level regarding open heart surgery. Conclusion: there was positive highly statistically significant correlation between total knowledge score, and total reported practices score of mothers regarding open heart surgery. Recommendation: Develop health educational program for mothers whose children had open heart surgery to increase mothers' understanding of open heart surgery, and their care for children with open heart surgery.