To identify whether Dickkopf-4 (DKK4) could be a potential biomarker for diagnosis and prognosis in patients with gastrointestinal stromal tumor (GIST). Serum was collected from 50 patients with GIST. Serological levels of DKK4 were examined by enzyme-linked immunosorbent assay (ELISA). The sensitivity and specificity was compared with modified NIH risk criteria. A 3-year follow-up was monitored to evaluate the correlation between DKK4 serum levels and relapse-free or overall survival. The expression of DKK4 in GIST tumor tissues was also evaluated using immunohistochemistry staining.