['B7-H4 is a novel B7 ligand that plays an important role in the T cell-mediated immune response as a negative regulator. Previous studies have suggested the aberrant expression of membrane B7-H4 in tumor cells. The aim of this study is to determine the expression levels of preoperative soluble B7-H4 (sB7-H4) in circulation and to investigate the correlations between sB7-H4 levels and clinicopathological parameters as well as the survival rate of patients with gastric cancer.', 'Blood specimens from 132 patients with gastric cancer and 63 healthy volunteers were analyzed by sandwich enzyme-linked immunosorbent assay.', 'Median concentrations of sB7-H4 in patients with gastric cancer were significantly higher than those in healthy volunteers (16.85 versus 10.46\xa0ng/mL; P\u2009=\u20090.008). Median levels of sB7-H4 were significantly correlated with tumor size, lymph node metastasis, the depth of tumor invasion and tumor-node-metastasis classification (P\u2009=\u20090.002, P\u2009=\u20090.001, P\u2009=\u20090.041 and P <0.001, respectively), but not with sex, age, tumor location or histological subtype (all P >0.05). Additionally, the overall survival rate was significantly lower in patients with high sB7-H4 levels when compared with low sB7-H4 levels (50.0% versus 77.3%, χ2\u2009=\u200910.78, P\u2009=\u20090.001). Moreover, multivariate analysis demonstrated that the risk of death was significantly higher in patients with high sB7-H4 levels than in those with low sB7-H4 levels (P\u2009=\u20090.039).'] Is serum B7-H4 expression a significant prognostic indicator for patients with gastric cancer?