Objective: Psoriatic arthritis (PsA) is a chronic inflammatory disease associated with psoriasis. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) is a large family of proteoglycanase enzymes that show proteolytic activity. The expression levels of ADAMTS proteases in osteoarthritis and rheumatoid arthritis are upregulated. However, their expression levels in PsA patients have not been examined yet. The aim of this study was to determine the serum levels of ADAMTS4 and ADAMTS8 in PsA patients. Materials and Methods: This was a case-control study and enrolled 40 PsA patients and 40 individuals as controls. Serum levels of ADAMTS4 and ADAMTS8 were examined by the enzyme-linked immunosorbent assay (ELISA). The relationship between ADAMTS8 levels and demographic and clinical features of PsA patients were analyzed. Results: The results of this study showed that the ADAMTS8 level was significantly elevated in the serum of PsA patients (160.9+-49.79 pg/mL) compared to the control groups (<15.6 pg/mL). An association (r=0.32, p<0.05) was detected between age and serum level of ADAMTS8. However, the level of the ADAMTS4 in many subjects was under the detectable range. Conclusion: Our results conclude that a relationship exists between ADAMTS8 and PsA, but further investigations are required to establish the function of ADAMTS8 proteases in PsA.