Maple Syrup Urine Disease is a disparity of leusin decarboxilation and isoleusin of valin defect that is synthesized with complex enzyme systems. It is a rare disease and represents disparity. In some cases can generate ketosis that grows according to health change and can cause comma. Dental treatment of a child with Maple Syrup Urine Disease was not clearly mentioned, there is only a factor such as infection which is very dangerous at any age and can generate irregular metabolism. Dental treatment of a child with Maple Syrup Urine Disease accompanied by mental retardation must to be done continuously to avoid infections that can result the death of the patient.