The aim of this study was to investigate the efficacy of serum glypican-6 (GPC-6) levels and the combination of N-terminal pro-B-type natriuretic peptide (NT-ProBNP)and GPC-6 in the diagnosis of heart failure (HF). In this prospective study, patients older than 18 years of age, admitted to the emergency department of our hospital between December 2021 and April 2022, diagnosed with heart failure (patient group),and healthy volunteers with similar sociodemographic characteristics (control group) were included. The disease severity classification of the patient group was made according to the 2021 ESC guidelines, using echocardiographic findings. Serum GPC-6 andNT-ProBNP levels were measured by the enzyme-linked immunosorbent assay (ELISA) method, which determines the antigen-antibody relationship. Optimal GPC-6 and NT-ProBNP levels for the diagnosis of HF were determined by receiver operating characteristic (ROC) analysis. The patients were divided into three groups according to these levels. Group 1 consisted of patients with both markers below the cutoff values, Group 2 consisted of patients with either of these markers above the cutoff values, and Group 3 consisted of patients with both markers above the cutoff values. The study included 65 heart failure patients and 20 healthy volunteers. When the patient and control groups were compared in terms of serum GPC-6 and serum NT-ProBNP levels, both parameters were evaluated as significantly higher in the patient group (p=0.038 and p<0.001; respectively). In the ROC analysis, it was determined that GPC-6 indicated HF with 58.46% sensitivity and 75% specificity for an optimal cutoff value of 390 pg/ml. In the ROC analysis, it was determined that serum NT-ProBNP indicated HF with 89.23% sensitivity and 70% specificity for an optimal cutoff value of 122 pg/ml. When the groups were compared according to the rate of HF, it was found to be higher in Group 3 compared to Group 2 (97.1% vs. 70.3%, p<0.002) and Group 1 (97.1% vs. 38.5%, p<0.001). This rate was seen to be significantly higher in Group 2 compared to Group 1 (70.3% vs. 38.5%, p=0.042). The combination of GPC-6 and NT-ProBNP may help diagnose HF patients admitted to the emergency department.