OBJECTIVES: The PedsQL™ Measurement Model is a modular approach to measuring health-related quality of life (HRQOL) in healthy children and adolescents and those with acute and chronic health conditions. Several Spanish versions for use in different Spanish speaking countries were developed. The objectives of this study were to compare these Spanish versions, quantify and qualify the differences and conclude on the need (or not) for country-specific Spanish versions. METHODS: Our study focused on the Teen form (13-18) and included the following steps: 1.Collection of the validated Spanish versions in collaboration with the author; 2.Identification of the differences in items, and response scales; and 3. Coding of the differences as Cultural (C), Lexical (L), Idiomatic (I) and Syntactical (S). RESULTS: Six validated Spanish versions were retrieved: Spanish for US, Spain, Argentina, Chile, Mexico and Peru. Since it was the first translated, the US Spanish version served as comparator. All versions showed differences. Spanish for Spain showed the highest number of differences (57), then Chile (47), Argentina (36), Peru (20) and Mexico (18). None of the differences were cultural. In 65% of the cases, the divergences were idiomatic. For instance, the expression “Se me hace difícil” (It is hard for me) used in US Spanish was replaced in all corresponding items by “Me cuesta” (Literally “It costs me”) in Spain, Argentina and Chile. The time recall sentence and item 3 of the School Functioning Scale showed most of the differences. One of the reasons could be the use of a very idiomatic form in the original US English version: “I have trouble keeping up”. It should be noted that items of the Emotional Functioning Scale showed very few differences. CONCLUSIONS: Numerous changes in wording for idiomatic reasons indicating respondents preferences point to the necessity of developing specific Spanish versions of the PedsQL™.