Background/aims: In the present study, the frequency of ErbB-2 overexpression and its relationship with pathologic parameters on patients with gastric cancer in Eastern Anatolia of Turkey was studied. Materials and Methods: A total of 32 newly diagnosed patients were enrolled in the study. DNA isolation was performed on paraffinized tumor tissues obtained from patients by endoscopy or surgical resection. ErbB-2 overexpression was investigated from the isolated DNA by "Real Time Polymerase Chain Reaction". Results: ErbB-2 positivity was detected in five (15.6%) of 32 gastric cancer patients. The correlation between distant metastases and ErbB-2 positivity was found to be statistically significant (p=0.04). Additionally, no statistically significant correlation was noted between ErbB-2 positivity and parameters such as level of differentiation (p=0.7), the depth of tumor invasion (p=0.08), lymph node metastases (p=0.6), Lauren's classification (p=0.4), World Health Organization classification (p=0.3), tumor, node, metastasis staging (p=0.3) and tumor localization (p=0.2). Lymph node involvement was present in all ErbB-2 positive patients, the depth of tumor invasion was T3 (one case) and T4 (four cases) with the cardia being the most common location, which was remarkable, though not statistically significant (p>0.05). All ErbB-2 positive patients were detected with intestinal-type gastric cancer according to Lauren's classification and with the tubular-type according to World Health Organization classification. Conclusion: According to our findings, given the rates ofErbB-2 overexpression (15.6%) in gastric cancer, the investigation ofErbB-2 overexpression as an important biomarker in humanized monoclonal-antibody treatment in patients with gastric cancer was considered appropriate.