Psoriatic onycho-pachydermo-periostitis has been recognized as an uncommon subset of psoriatic arthritis, and to date, only a few cases have been reported. In general, psoriatic onycho-pachydermo-periostitis is regarded as a unique variant of psoriatic arthritis, but its pathology and pathophysiology are not well understood. Although psoriatic onychopachydermo- periostitis is usually found in patients with psoriasis, it can also be found in patients without psoriatic skin lesions. It is characterized by psoriatic nail changes (usually onycholysis), painful swelling of the soft tissue close to the distal phalanges, and radiographic changes of the distal phalanges with periosteal reaction and bone erosions. We present a 58-year-old man with a 3-year history of deformation, thickened nails and pustules on the skin of his fingers and toes, and painful redness of the nail bed accompanied with pain in small joints. The family history was negative. After confirmation of the diagnosis, methotrexate: 15 mg weekly, was initiated which led to symptoms improvement. Treatment of psoriatic onycho-pachydermo-periostitis is difficult. It is based on treatment modalities used for other forms of psoriatic arthritis, such as sulphasalazine, methotrexate, and anti-tumor necrosis factor antibody therapy with adalimumab and etanercept. Nonsteroidal anti-inflammatory drugs are usually ineffective. Retinoids, subungual cyclosporine and corticosteroid therapy also showed inefficient. In our patient, methotrexate has shown efficacy in symptom improvement.