Introduction: Anterior open bite is defined as lack of vertical overlap between the upper incisors and the lower incisors in centric occlusion. It is considered one of the difficult malocclusion problems that face orthodontist in daily practice. Many studies on the prevalence of anterior open bite in different population all over the world were done yet; none was done before on the Egyptian population. Aim of the sudy: The aim of the present study was to investigate the prevalence of anterior open bite in a sample of Egyptian adolescent population. Material and methods: The study comprised a sample of 5000 student selected randomly from different schools of different governorates of Egypt (Cairo, Giza, Helwan, Saini, Minya and Dakahlia) after the approval of Ministry of Health (Central Directorate for Research and Health Development). The sample was equally divided into two groups according to the gender. All the students were quickly reviewed using disposable mirrors and the parameters considered included ( The amount and extension of anterior open bite, molar and canine relation, abnormal habits , oral hygiene, gingival condition and tongue behavior and size ). The following results and conclusions were extracted out of the study: 1. The prevalence of anterior open bite among Egyptian adolescent population was 1.6%. 2. The incidence of anterior open bite was found to be more in girls than in boys with a ratio of (5: 3). 3. Anterior open bite was found mainly in association with Class I followed by Class III and Class II respectively. 4. Anterior open bite was usually associated with tongue thrust and mouth breathing as etiological factor.