Proteus syndrome is an extremely rare congenital disorder with progressive asymmetric overgrowth of multiple tissues. The etiology is unknown to date. The aim of this article was to describe the clinical and radiographic periodontal findings and other oral manifestations in a patient with Proteus syndrome. A 13-year-old Caucasian Brazilian girl with Proteus syndrome was evaluated by means of clinical examination and full-mouth intraoral radiographic analysis. The patient showed skeletal malformations; gigantism; facial phenotype; and overgrowth of multiple tissues, including disproportionate overgrowth of skull, left hand, and lower limbs. Evaluation of the plantar surface of the left foot showed cerebriform connective nevus. The hands also showed reduced range of motion. Intraoral examination revealed enamel hypoplasia of permanent teeth restricted to the left side of the mouth, generalized gingival overgrowth, abundant dental plaque, and malpositioned teeth. Neither periodontal pockets nor alveolar bone destruction were detected. In conclusion, oral manifestations of Proteus syndrome may include gingival overgrowth and malposition of teeth, as well as unilateral enamel hypoplasia, as shown in this case report.