Apert syndrome is a rare genetic disorder characterized by craniosynostosis, midface hypoplasia and syndactyly of both hands and feet. Herein, we report a case of severe hyperhidrosis in a 13-month-old girl with Apert syndrome who was born with malformations of the skull, face, hands and feet. The patient had a history of excessive sweating since birth, and the symptom was confirmed via iodine-starch test. Hyperhidrosis was first reported in 1993 as one of the key cutaneous manifestations of Apert syndrome. Since then, however, there was a great lack of subsequent studies. Instead, the main focus in the field of dermatology has been on the antibiotic-refractory acne, another cutaneous hallmark in Apert syndrome. Our case is the first report of hyperhidrosis in Apert syndrome in Korean literature. We reemphasize hyperhidrosis as a key skin manifestation in Apert syndrome.