INTRODUCTION: Oral health related quality of life measure has a great importance at all levels of dental research, it helps to plan evidence based public health policies and indicates how resource allocation should be done. OBJECTIVES: The aim of this study was to assess the Child-OIDPQ reliability and validity for application among Egyptian children aged 11-12-year-old, as well as determining the prevalence and causes of oral impacts on daily performances in public and private school children in Alexandria. MATERIALS AND METHODS: Cross-sectional survey performed on 410 randomly selected student aged 11–12 years in the middle district of Alexandria city, Egypt. Data were collected through a self-administered questionnaire; Child-Oral Impacts on Daily Performances questionnaire (Child-OIDP). RESULTS: The instrument showed acceptable psychometric properties and is considered as a valid, reliable and practical inventory for use among the Egyptian sample. (Cronbach's alpha 0.71 for severity and 0. 70 for frequency). The prevalence of oral impacts was high (85.4 %) of children experiencing some kind of oral conditions affecting their daily life during the past three months. The highest impact was reported on eating (61.9%) followed by cleaning (46.3%) and the lowest impact was on speaking (21.0%). Tooth pain was one of the main perceived causes of impacts on the following 5 performances: duties (35.9%), emotional status (11.1%), sleeping (42.2%), eating (32.0%) and speaking (16.7%). there was no statistically significant difference detected by Mont Carlo exact probability test in the intensity effect of impact between public and private schools CONCLUSIONS: It was concluded that the Child-OIDP questionnaire can be applied to Egyptian children as a valid measure of oral health related quality of life.