Objective To investigate the expressions of interleukin-33 (IL-33),soluble growth stimulation expressed gene 2 (sST2) and transforming growth factor β1 (TGF-β1) in the patients with systemic sclerosis (SSc) and their correlations.Methods Serum IL-33,sST2 and TGF-β1 levels from 25 SSc patients and 25 healthy controls were determined by an enzyme linked immunosorbent assay (ELISA).The expressions of IL-33 in the damaged skin tissue of SSc patients and normal skin tissue were detected with the immunohistochemical staining.Results Serum IL-33 and TGF-β1 levels in SSc patients were significantly higher than that in healthy controls (P ＜ 0.05),and serum IL-33 levels were positively correlated with TGF-β1 levels in SSc patients (P ＜ 0.05).Immunohistochemical staining results showed that the expression level of IL-33 in the damaged skin tissue of SSc patients were significantly higher than that in normal skin tissue (P ＜ 0.05).However,there was no significant difference in the expression level of sST2 between SSc patinets and healthy controls.Conclusion Serum IL-33 levels in SSc patients increase significantly,which is correlated with the expression of TGF-β1,indicating that IL-33 may play an important role in the process of inflammation and fibrosis of SSc via the regulation of TGF-β1.