AIM: The aim of the study was to analyze whether COVID-19 cause a delay in the diagnosis of gastric cancer patients particularly in the TNM staging of the tumor, or not. MATERIAL AND METHODS: This retrospective single-center study included the patients diagnosed with gastric cancer from March, 2019 to December 2020. The patients were divided into two groups: baseline and the pandemic groups. The following parameters were compared between the groups; demographic data, numbers of newly diagnosed patients, type of the surgery, location of the tumor, frequency of neoadjuvant treatment, ASA score, length of hospital stay, clinical staging and pathologic TNM staging. RESULTS: The mean monthly number of newly diagnosed gastric cancer patients showed a significant decline from 7.5 to 5.6 (p< .001). There were no statistically significant differences between the groups with regard to the demographic factors, except CA 19-9 levels. Patients in the pandemic group had higher both clinical and pathological T-stages (p < 0.05). CONCLUSIONS: Our study showed a decline in the number of the newly diagnosed patients with gastric cancer during the pandemic and also more patients presented with advanced stage during the pandemic period. This study showed that the pandemic causes a potential delay in the diagnosis of gastric cancer patients.