Obesity is a major public health concern internationally and this study aims to identify the Prevalence of obesity in mentally disabled children in special education centers in Khartoum state. This study was conducted at the forty special education institutes in Khartoum state including its seven governorates (Khartoum, Jabal Olia, Omdurman, Karary, Ambdh, Bahry, and East Nile). The number of children was 290 children; 190 males and 100 females at age of 10-18 years. This is a descriptive study to identify the Prevalence of obesity in mentally disabled children in special education centers in Khartoum state. Obesity was defined according to the child's percentage weight for height. All children had an Intelligence Quotient (I.Q) test carried out within the last six months prior to the start of this study. Intelligence Quotient (I.Q) test was conducted using the Stanford – Binet test that was adapted to the Sudanese culture by Malik Badri. The study showed that the prevalence of the obesity in mentally disabled children is 28.3% where it reaches 27.4% in males and 30.0% in females. The prevalence of the obesity is insignificant associated with sex, age or Intelligence Quotient of the children. Nutrition care should be incorporated in the multi-dimensional care for such group of children.