A reliable biomarker of disease activity in psoriasis would be helpful for management, especially if this gave early information on treatment efficacy. This study investigated whether serum levels of soluble (s)CD163 correlated with psoriasis activity as assessed by the Psoriasis Area and Severity Index (PASI). CD163, a glycoprotein molecule expressed on macrophages and dendritic cells, is cleaved from the surface of these cells in some inflammatory diseases, and sCD163 levels have been shown to correlate with disease activity in other disorders. In this study, levels of sCD163 did not correlate with PASI in the patients (P = 0.56). Five patients had moderately increased PASI (12.6–20.3) but their sCD163 levels were within the normal range. From this study, it seems that sCD163 levels do not correlate with the inflammatory process in the skin of patients with psoriasis and thus sCD163 is not likely to be a useful biomarker for this disease.