The present study was undertaken to assess the prevalence of malocclusion and orthodontic treatment need using the Index of Orthodontic Treatment Need in a group of Egyptian school children in Port Said and Domyat governorates. This study was a part of a research project between the Ministry of Education, Ministry of Health and the Orthodontic department representing the Faculty of Oral and Dental Medicine, Cairo University which included seven separate studies in different Egyptian governorates. Port Said governorate was divided into seven regions ; while Domyat Governorate was divided into four regions according to geographical location, one school was chosen randomly from each region thus, seven schools from Port Said governorate and four schools from Domyat Governorate were included in the study. A total of 1300 students (52.9% males and 47.1% females) from Port Said and 300 students (47% male and 53% female) from Domyat, aged 8 to 12 years who had not undergone orthodontic treatment were randomly selected from public schools in both governorates. The randomly-chosen students were school children of both genders born to Egyptian parents and those who did not meet the inclusion criteria were excluded from the sample. A letter was sent to the parents of all students to seek consent for their cooperation in the study. Clinical examination was performed with the cooperation of the health care specialist where each student was seated on an ordinary chair with the head in an upright position and was instructed to occlude on his posterior teeth to assess anteroposterior, vertical and transverse dental relations including molar relation, overjet, overbite and crossbite. Each child was then asked to open his/her mouth for intra-arch dental assessment including displacement, missed teeth, supernumerary teeth, submerged (ankylosed) teeth, impeded eruption of teeth and cleft of lib and/or palate. Intaoral frontal photograph was taken for each child on centric occlusion for assessment of aesthetic component ( AC ) of IOTN .The ( AC ) and ( DHC) grade was evaluated and recorded for each child to assess the index of orthodontic treatment need in both governorates. Based on the findings of this study, the following conclusions can be stated: In Port Said and Domyat, school children with accepted occlusion represented 30.8% and 38.5% of the total sample while, malocclusion represented 69.2% and 61.5% of the total sample respectively, of which 53.5% and 46.5% showed Angle Class I, 8.8% and 8% showed Angle Class II, 6.4% and 6.7% showed Angle Class III and 0.6% and 0.3% showed Angle Class IV in Port Said and Domyat governorates respectively. Compared to previous Egyptian studies, there was a tendency toward increase in the prevalence of accepted occlusion and in the prevalence of Angle Class II and III malocclusion. There were no significant difference for all occlusal categories between males and females, early and late mixed dentition groups in Port Said and Domyat Governorate. Dental health Component (DHC) of the Index of Orthodontic Treatment Need showed that 8.2% ,5.3%of the total sample were in great need of treatment, 15.5%,25% showed moderate need, while 76.2% ,69% showed no or little need for treatment in Port Said and Domyat, respectively. Aesthetic component (AC) of the Index of Orthodontic Treatment Need showed that 7.2% ,6% of the total sample were in great need of treatment, 28.2%, 11% showed moderate need, while 64.7%, 83.7% showed no or little need for treatment in Portsaid and Domyat respectively. In both governorates, there was no significant difference for DHC and AC between males and females. There was a statistically significant difference of (DHC) between early andlate mixed dentition groups in Portsaidgovernorate as early mixed dentition showed higher prevalence of moderate need 31.9%.on the other hand there was no statistically significant difference of (DHC) between early and late mixed dentition groups in Domyat Governorate. There were no correlation between either of DHC or AC components and mixed dentition stages.