Background: Since obesity is a global medical condition which affect adults and children of both sexes and lead to many diseases including hypertension, stroke and diabetes mellitus-2, it is chosen to assess the prevalence of the obesity and its predisposing factors among the primary school children in Willayat of Nizwa, AL-Dakhylliya Governorate, Sultanate of Oman during the period of November 2019 -February 2020.Methods: This study was carried out in four different primary schools; 2 boy's and 2 girl's primary schools by using a self-administered questionnaires for 270 males and 270 females (grades 5 th and 6 th ) school children whose ages range from 11 and 12 years. The study was approved by the School of Pharmacy, College of Pharmacy and Nursing, University of Nizwa as a graduation project and permitted by the General Directorate of Education in Al-Dakhylliya Governorate. The questionnaires included demographic parameters and other variables for the school's children, in addition to separate questionnaires for the teachers of the schools and the parents or the guardians of the school children. These questionnaires were chosen from previous similar studies and modified in order to obtain the required information for the study. Consent forms were prepared to seek the permission of the guardians and the school teachers to perform this study for ethical considerations. All findings are illustrated in a histogram and the important related issues are discussed.Results: Out of the total number of the 540 primary school children and of equal number of boys and girls investigated in this study (270 each), it was found that the average values of the overweight are 10.25%, Obesity-1 equals to 3.45%, obesity-2 is 2.45%. Normal values of BMI are 27.5% and the underweight is 57.5%. The majority of the school children (81% females and 51% males) in the schools investigated reported that they do not have a family history of obesity.