Background: Children with mental retardation require intensive care by parents to optimize their developmental stages such as conducting medical examinations, counseling and coaching. family members are the most important part for children with mental retardation to be able to live their lives well. Aim: to  explore burden of family caregivers for the children of mental retardation  at Port-Said City. Subjects and Method: A descriptive cross-sectional research design was used at the only governmental schools for mental retardation in Port Said and Port Fouad city namely Intellectual Educational schools. Purposive sampling was be used. Two tools used to gather the required data consisted of; Tool (1) Astructured self administer  questionnaire Tool (2) burden scale. Results: The study revealed that(20.0 %) of the studied family caregivers had no burden, followed by (32.2 %) of them had mild burden while (41.7 %) of them had moderate burden, and finally (6.1 %) of the studied family caregivers had sever burden. Conclusion: It can be concluded that about tow fifth of the studied family caregivers had moderate level of burden. Recommendations: Designing and training program to caregivers regarding coping and rehabilitation for their roles to their mentally retarded children. Special financial support should be given to these families to help them to meet extra demands and costs of caring their mental retarded children.