Gastroesophageal reflux disease (GERD) constitutes a significant health problem in societies of high socioeconomic status. The notion of quality of life is broader than the definition of health and encompasses two aspects: the subjective and objective one. The tools used for the evaluation of quality of life are questionnaires.The aim of the study was the evaluation of the original quality of life questionnaire in patients with gastroesophageal reflux disease treated for 4 weeks with a single dose of omeprazole at 20 mg daily.Material and methods. The original quality of life questionnaire was formulated based on the Likert method. Four time levels of complaint persistence were introduced. The patients were asked 10 questions with earlier prepared answers marked by the respondents. Each of the questions corresponded to a certain time level of complaint persistence. The data obtained from the questionnaires were subject to statistical analysis. The studies were conducted on a group of 10,623 patients. Adequate methods were used in the statistical analysis of data from obtained answers. The significance threshold for each of the studies was p < 0.01, which means that the obtained conclusions are true with the probability of at least 99%. The majority of statistical calculations were performed with the use of STATISTICA 7.0 and Excel software.Results. Improvement of quality of life was found in all the studied aspects: physical (questions 1, 3, 4, 5, 7), functional (question 6), emotional (questions 2, 10) and social (questions 8, 9). No correlation with age or gender was found. The analysis of test correctness was conducted, revealing reliability, validity, sensitivity, appropriateness and practicality of the questionnaire.Conclusions. 1. The original quality of life questionnaire meets the requirements for the tools evaluating quality of life in gastroesophageal reflux disease. 2. The usefulness of questionnaire was confirmed in a group of 10,623 patients with gastroesophageal reflux disease in the Polish population. 3. The questionnaire equals the international tests, while its advantages are the ease of completion and high level of perception.