Prader-Willi syndrome (PWS) is a neurobehavioral genetic disease whose cause is failure on chromosome 15. It is considered the primary genetic cause of obesity, since it is characterized by hyperphagia. Although the scientific literature will produce articles on Prader-Willi syndrome, few reported oral conditions of these patients. Objective: This study aimed to describe the oral health status of a patient diagnosed with PWS. Case report:A boy aged 10 years-old, leucoderma, attended the Discipline of Dentistry for Special Care Patients, Pontifical Catholic University of Paraná (PUCPR), with all the inherent PWS characteristics such as hyperphagia and obesity. Clinical, radiographic and laboratory tests were performed to verify the oral health conditions which showed the presence of biofilm accumulation, gingivitis and a high DMFT index. It was necessary to adequate oral environment through extractions, restorations, and prophylactic therapy. Conclusion: Considering the information obtained, it was concluded that the motivation to maintain oral health should be constant for this patient and involve family, since hyperphagia, which is a determinant for obesity, decisively contributes to the evolution of oral diseases.