Background: Hypospadias is one of the commonest conditions seen in pediatric urology practice, genetic and environmental factors play a significant role in its etiology. Post-operative nursing care of hypospadias repair is directed toward preventing infection and instructing parents in home care of the child. Aim of the study: The aim of the current study was to evaluate the impact of pre-operative instructions regarding hypospadias repair on mothers' knowledge, practices andselected post-operative outcomes. Research design: Quasi-experimental research design (pre-posttest) was used in the current study. Setting: The current study was conducted at in-patient surgery unit at Minia university hospital for obstetric and pediatric, which located in Minia city. Subjects: A purposeful sample of 100 mothers of children with hypospadias was participated in the study. 50 for (study group) and 50 for (control group). Research tools:Tool (I): A structured interview questionnaire: it covered sociodemographic data of mothers and data of child and mothers' knowledge about hypospadias repair; Tool (II): Observational checklist about diaper care; Tool (III): Post-operative outcomes assessment record. Results: It was illustrated that vast majority of mothers in the study group had satisfactory level of knowledge about hypospadias repair compared to minority in control group in post/test with highly statistically significant differences P-value at 0.001. As well as almost of the mothers in the post-test in the study group had appropriate level of practice in relation to diaper care. On the other hand, minority of children in the study group had less postoperative complication at the first postoperative day, 7^th day after surgical repair  and at  1^st  month of surgical repair compared to control group.Conclusion: The study concluded that the preoperative instructions for mothers of children with hypospadias were effective by means of marked improvement of knowledge, practices and selected post-operative .Recommendation: The study recommended thatdevelopingcontinuous training session to pediatric surgical nurses and educational sessions for mothers about preoperative instructions regarding hypospadias repair would improve mothers' knowledge, practices and selected postoperative outcomes.