Abstract: Objective To investigate serum levels and mRNA expressions of tumor necrosis factor-like weak inducer of apoptosis （TWEAK） and its receptor CD163 from the patients with psoriasis vulgaris (PV). Methods Peripheral blood samples were obtained from 28 patients with PV and 15 healthy control subjects. Serum levels of TWEAK and CD163 were detected by ELISA, mRNA expressions of TWEAK and CD163 in peripheral blood were analyzed by real time-PCR, and protein expressions of TWEAK and CD163 were determined by flow cytometry. Results All the 28 PV patients were in progressive stage at the beginning of this study, 10 patients then recovered in convalescent stage after treatment. Compared to healthy controls, PV patients had higher serum TWEAK levels and lower serum CD163 levels. Serum TWEAK level in progressive stage was significantly higher than that in convalescent stage. Serum CD163 level were elevated significantly in convalescent stage compared with those in progressive stage. TWEAK mRNA expression in PV patients were significantly lower than that in healthy controls, but there was no significant differences of CD163 mRNA expression. TWEAK expression in monocytes in progressive stage and convalescent stage were significantly higher than that of controls, CD163 expression in monocytes in progressive stage and convalescent stage significantly lower than that in controls. No correlations wene found between psoriasis area and severity index (PASI) score and expression of TWEAK and CD163. Conclusion TWEAK/CD163 pathway may play a role in PV.