OBJECTIVES: To obtain the multi-attribute utility function (MAUF) for the Spanish version of the Short Form 6-D (SF-6D) and to compare utilities values with those determined by the British MAUF. To determine the weights of SF-36v1 items conforming the SF-6D instrument. METHODS: A whole-nation representative sample of 2,549 subjects [48.9% men, 48.5 (14.01) years] with mild to severe degree of Gastroesophageal Reflux Disease was recruited by 500 clinicians selected at random and used for this analysis. The Spanish versions of SF-6D and EQ-5D questionnaires plus the corresponding visual analogue scale were self-completed. Attribute weights were estimated using a categorical regression model. First the estimation procedure was validated through estimation of the MAUF for the EQ-5D attributes based on the exiting Spanish tariff scores for the instrument. Secondly the MAUF for the SF-6D attributes was estimated regressed on the EQ-5D tariff scores. Weights were rescaled to yield scores ranging from worse possible state (0) to full health (1). RESULTS: All estimated attribute weights were significant and goodness of fit was reasonable (R2=0.799). Spanish utility values for the same health states are significantly different from those used in the UK; 0.7458 (0.208) vs. 0.7090 (0.143), p<0.001. The shape of utility scores obtained with the Spanish MAUF exhibits a cubic pattern as compared to the British. Utilities obtained by the Spanish MAUF are higher for benign health states while severe states attain lower utilities. CONCLUSION: The proposed method allows for a valid and reliable estimation of a MAUF based on kwon utilities of a concurrent instrument, avoiding the need of incomplete designs to collect preferences. Evident differences between culture specific scoring systems encourage adapting instruments to the target culture in order to obtain valid measures. Spanish weights for SF-6D are now available to be used with existing or new SF-36v1 databases.