The aim of this study was to validate the European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire Core 30 (QLQ-C30) and its esophagi-gastric module (QLQ-OG25) in their Polish language versions. Translation of the QLQ-OG25 was done according to EORTC guidelines. Each of the 98 patients filled out the two EORTC questionnaires and a personal questionnaire. Reliability and validity test were performed and patients' comments were analyzed. The Polish version of the EORTC QLQ-C30 and the QLQ-OG25 are reliable and valid tools for measuring health-related quality of life in patients with esophagi-gastric cancer.