OBJECTIVES: The short, self-administered Gastroesophageal Reflux Disease (GERD) Symptom Frequency Questionnaire (GSFQ) is a specific Quality of Life (QoL) instrument which measures the impact of GERD symptoms on QoL. This study aims to adapt the GSFQ into Spanish (for Spain) culture and check the questionnaire psychometric properties. METHODS: An expert panel composed by a gastroenterologist, two methodologists, one expert in clinical research and one pharmacoeconomist supervised the adaptation process. The original instrument was translated and back-translated by two independent translators. For psychometric measures, a small sample was used to check the initial comprehension and factibility. A national representative sample was selected, stratified by gender, age (<45, =45 years) and GERD severity (0-I, =II, Savary-Miller score). Content validity was ensured by the original instrument. Cronbach's Alfa was used to assess reliability, and exploratory factor analysis to assess dimensionality. The EuroQol questionnaire and corresponding Visual analogue scales (VAS) were used for concurrent validity. RESULTS: A total of 3997 patients with pyrosis symptoms were recruited by 490 clinicians. Mean age was 49.35 (14.35) years and 48.4% were women. No ceiling or floor effects were detected in item responses. The reliability was good (0.864) and only 1 dimension exhibited an eigenvalue (3.45) above 1, explaining 58% of available variability. All items loaded on this dimension. Correlation were moderate but significant (p<0.001) with EuroQol (0.499) and VAS (-0.481). The average score was 34.17 (19.685), in the 0-100 scale. Mean scores were significantly different between GERD diagnosed severity levels (F4, 33035 = 84.9, p <0.005), but no differences were found between Savary-Miller level IV and levels II-III. CONCLUSION: The Spanish version of the GSFQ has good psychometric properties, behaves as a unidimensional scale, and is capable to discriminate between patients with varying degrees of GERD severity.