PURPOSE: There has been little information about the impact of coronavirus disease 2019 (COVID-19) pandemic on esophagogastroduodenoscopy (EGD) and gastric cancer claims. This study aimed to measure the impact of COVID-19 pandemic on EGD and gastric cancer claims in South Korea. MATERIALS AND METHODS: This nationwide, population-based study compared the claims data of EGD, gastric cancer, early gastric cancer (EGC), advanced gastric cancer (AGC) and gastric cancer operation in 2020 and 2021 (COVID-19 era) to those in 2019 (before COVID-19 pandemic). RESULTS: The annual claims of EGD, gastric cancer, EGC, and AGC were reduced by 6.3%, 5.0%, 4.7%, and 3.6% in 2020 and by 2.2%, 1.0%, 0.6%, and 1.9% in 2021, respectively, compared to 2019. The amount of annual claims of gastric cancer operation was reduced by 8.8% in 2020, but increased by 0.9% in 2021, compared to those in 2019. The monthly claims of EGD, gastric cancer, EGC, AGC, and gastric cancer operation were mainly reduced in the first epidemic wave of COVID-19, but decreased in the 2nd to 4th epidemic wave. Compared to 2019, the monthly claim of EGD, gastric cancer, EGC, AGC, and gastric cancer operation were reduced by 28.8%, 14.3%, 18.1%, 9.2%, and 5.8% in March 2020 and by 17.2%, 10.8%, 10.3%, 7.2%, and 35.4% in April 2020, respectively. CONCLUSION: Negative impact of the COVID-19 pandemic on EGD, gastric cancer, EGC, AGC, and gastric cancer operation was worst during the first surge of COVID-19, but decreased in the 2nd to 4th epidemic wave of the disease in 2020 and 2021.