Background: The Attention-Deficit/Hyperactivity-Disorder (ADHD) is a common neurobehavioral childhood problem with negative impacts on child and parents. The aim of this study was to evaluate the effect of a nursing intervention program on stress and competence of parents of ADHD children. Subjects &Methods: Research Design: A quasi-experimental study was utilized in this study. Settings: The study was conducted in the outpatient psychiatric clinic in El Mabarra and El Ahrar Hospitals at Zagazig city on 50 parents and their children with ADHD. Tools: Data were collected through interviewing parents using the Parenting Stress Index (PSI), the Parenting Sense of Competence (PSOC), and the ADHD checklist. The researcher designed and implemented the intervention program responding to the identified parents' needs. The work lasted from October 2014 to May 2015. results revealed that children's age ranged from 4 to 14 years, with 76.0% males. After the intervention, statistically significant improvements were revealed in parenting satisfaction, efficacy, and PSOC; child-related, parent-related, and total PSI (p<0.001). ADHD improved among 78% after the intervention (p<0.001). Statistically significant negative correlations were found between the scores of parents' satisfaction, competence, and PSOC from one side and each of the child-related, parent-related, PSI, and ADHD scores. In conclusion, the implementation of an educational intervention to the parents of children with ADHD is effective in improving their parenting satisfaction, efficacy, and PSOC, with reduction in their stress, and improvement of child abnormal behaviors. Recommendations: It is recommended to apply the developed program in the study settings for more improvements. The school health team needs to be trained in screening and early detection, with counseling clinics for parents of ADHD children.