It has been known for many years that psoriasis is associated with increased activity of various types of MMPs [9]; however, presented in this study are results which for the first time clearly indicate that in the case of plasma MMPs with collagenase or stromelysin activity, there are no differences between PsV and PsA patients, while gelatinases such as MMP-2 and MMP-9 significantly differentiate these two types of psoriasis. The gene discussed is MMP9; the disease is psoriasis.