Pachydermoperiostosis (PDP) is a syndrome characterized by digital clubbing of fingers and toes, thickening of the scalp and face, hyperhidrosis, accumulation of new bone tissue together with arthralgia. It is a primary form of hypertrophic osteoarthropathy which, unlike secondary osteoarthropathy, is not associated with coexisting systemic diseases. Pachydermoperiostosis is a rare disease, diagnosed in only 5% of patients with confirmed primary osteoarthropathy. Aim. The aim of this paper was to describe a case of a male patient with PDP, treated at the Department of Orthodontics, the Medical University of Warsaw. Case report. A 24-year-old male patient presented at the Department of Orthodontics, the Medical University of Warsaw, to treat a malocclusion. The clinical examination revealed thickened skin, digital clubbing, thickened and deformed bones, ptosis, seborrhoea and hyperhidrosis. During the dental examination, the following were observed: numerous cavities, missing teeth, distoclusion with protrusion of incisors and dental abnormalities, gothic palate and significant hypertrophy and inflammation of the gingivae, which appeared with accompanying systemic symptoms. Literature reports cases with a similar clinical picture. Discussion. On the basis of characteristic clinical symptoms, radiological pictures of bones of wrists, lower legs and skull, and blood morphology, pachydermoperiostosis was diagnosed. Summary. Due to the rare occurrence and similarity to other disease entities, such as acromegaly, secondary osteoarthropathy, rheumatoid arthritis or thyroid acropachy, the diagnosis of this disease is extremely difficult. Treatment of PDP is multispecialist, and includes both pharmacological and surgical treatment. (Niewęgłowska A, Pietrzak-Bilińska B, Kowalski J, Zadurska M. Pachydermoperiostosis – case report. Orthod Forum 2020; 16 (1): 68-76).