Objective To evaluate levels of the calcium-binding proteins S100A8 and S100A9 in the skin of patients with psoriatic arthritis. Methods Skin punch biopsies were obtained from patients with psoriatic arthritis and healthy control subjects. S100A8/A9 were semiquantified via immunohistochemistry and semiquantitative polymerase chain reaction. Results The study included biopsies from nine patients with psoriatic arthritis and nine control subjects. S100A8 and S100A9 were present at visibly higher levels in psoriatic plaques compared with normal skin samples. S100A8 and S100A9 RNA levels were significantly higher in the peripheral region of plaques compared with the central region. Conclusion Both S100A8 and S100A9 may represent good therapeutic targets in psoriasis and psoriatic arthritis.