Introduction: Mucopolysaccharidoses are rare diseases related to chronic metabolic conditions caused by a genetic mutation that results in the deficiency of lysosomal enzymes responsible for the degradation of glycosaminoglycans, causing alterations in the normal functioning of the organism and oral alterations. Aim: To evaluate the physical, systemic and oral characteristics of two sibling patients with mucopolysaccharidosis type IV-A found in patients treated at the Special Patients Outpatient Clinic of the University of Ribeirão Preto - Unaerp. Cases Report: Clinical Case 1: Female patient, 34 years old; and Clinical Case 2: Male patient, 31 years old. In Clinical Case 1, the following clinical and physical characteristics were observed: respiratory difficulty, bone changes in the arms, valgus deformities of the knees, enlarged thorax, dysostosis with changes in the hands, decreased hearing, rheumatological problems, difficulty in locomotion, changes in motor coordination, short stature, shortened neck and trunk. Regarding oral changes: taurodontia in upper and lower molars, supernumerary tooth, low mandibular height, macroglossia, anterior open bite, vestibular exostoses, dental erosion on the occlusal and palatal/lingual surfaces in almost all teeth, limited mouth opening, atypical swallowing and deep palate. In Clinical Case 2, the same clinical and oral characteristics were observed, except: supernumerary tooth and vestibular exostoses. Conclusion: MPS is a rare disease that affects organs and tissues, requiring lifelong multidisciplinary health treatment, as there is no cure. However, dental treatment is important to contribute to the individual's quality of life
