The objective of this study is to assess the serum IL-35 level and its association with clinical manifestations in patients with systemic sclerosis (SSc). IL-35 serum levels were measured by ELISA from 56 patients with SSc and 53 healthy controls. Association of IL-35 serum levels were sought with clinical parameters. Serum IL-35 levels were significantly higher in SSc patients (5.08 ± 0.76 pg/ml) than in healthy individuals (1.89 ± 0.69 pg/ml; p < 0.0001). Patients with lung fibrosis had higher IL-35 levels than those without fibrosis (7.75 ± 1.36 and 3.08 ± 0.70 pg/ml, respectively, p = 0.0022). IL-35 is elevated in the serum of patients with SSc and is associated with lung fibrosis. Our findings suggest that this cytokine can have a role in fibrotic diseases, but further studies are needed to address the role of IL-35 in the pathogenesis of SSc.