Introduction. Hepatocellular carcinoma (HCC) is a malignancy that primarily affects patients with liver cirrhosis. Early diagnosis is crucial for improving patient outcomes. The study aimed to investigate the potential role of glypican-3 (GPC3) serum levels, both alone and in combination with alpha-fetoprotein (AFP) and gamma-glutamyl transpeptidase (GGT) serum levels, as diagnostic biomarkers for HCC. Methods. The study included 53 patients with liver cirrhosis and confirmed HCC, who were admitted to the Department of Infectious Diseases, Tropical Diseases and Hepatology at the Medical University of Warsaw, Warsaw, Poland, underwent physical examination and laboratory testing and were compared with 29 healthy volunteers. GPC3, along with demographic data, Child-Pugh and Model for End-Stage Liver Disease (MELD) scores, AFP, and GGT levels, was analyzed in relation to HCC diagnosis. The sensitivity and specificity of GPC3 alone and in combination with AFP and GGT were evaluated for diagnosing HCC. Results. The difference in serum GPC3 levels between patients with HCC and the control group was statistically insignificant (p=0.765). However, a significant correlation was found between GPC3 and AFP serum levels in patients with HCC (p=0.009). Additionally, a correlation was observed between higher GPC3 serum levels within the normal range and the occurrence of HCC. The sensitivity for GPC3 levels greater than 75 ng/ml for detecting HCC was 93.1%, while the specificity was 49.1%. The utility of GPC3, when combined with AFP and GGT, was inconsistent across different thresholds in detecting HCC. Conclusions. The serum levels of GPC3 do not provide satisfactory effectiveness in detecting HCC, and the disease can occur in patients with GPC3 serum concentrations within the normal range. In patients with liver cirrhosis, serum GPC3 levels above 75.00 ng/ml may suggest an increased risk of HCC development. Additionally, the combination of AFP, GPC3, and GGT demonstrates some utility in detecting HCC; however, it shows no superiority over GPC3 alone.