BACKGROUND:The new biochemical marker, signal peptide-CUB-EGF domain-containing protein 1 (SCUBE1), is secreted and cell surface glycoprotein expressed during early embryogenesis. The protein is found in platelet and endothelial cells. Crimean-Congo hemorrhagic fever (CCHF), which is caused by a tick-borne virus belonging to the Bunyaviridae family, may present with a mild clinical course or may exhibit a severe profile with potentially fatal hemorrhaging. The aim of this study was to determine the diagnostic and prognostic significance of SCUBE1 levels in CCHF. METHODS:This study was conducted with patients with CCHF. SCUBE1 levels in patients with CCHF were determined using an ELISA. RESULTS:SCUBE1 titers of CCHF patients were significantly higher compared to those of the control group (p=0.0001). SCUBE1 levels of patients with hemorrhage were significantly higher than those of patients without hemorrhage (p=0.0001). SCUBE1 values of patients who died were significantly higher than those of the survivors (p=0.012). CONCLUSIONS:SCUBE1 levels are a new biomarker that can be used in the differential diagnosis and monitoring of patients hospitalized with suspected CCHF. These levels are also significant as potential predictors of mortality.