This study compares the differences in the curricular emphases in mathematics in Brazil and Portugal using the results from the Programme for International Student Assessment (PISA) in 2003. The participants of this programme are 15-year-old students from the member countries of the Organisation for Economic Co-operation and Development (OECD) and from partner countries. Its aim is to assess how these students master the essential skills and knowledge to meet real- life challenges. Based on the existing literature about the official, taught and learned curricula, this study assumes that the results of several countries in international surveys constitute a strategy for analysing the learned curriculum and the pedagogical emphases in the mathematical area. The methodology used in this work to identify the curricular differences as well as the pedagogical and sociocultural approaches is the analysis of the Differential Item Functioning (DIF). One item presents a differential functioning when students from different countries, who have the same cognitive ability, do not have the same probability of answering the item correctly. The results show that some mathematics items present differential functioning between Brazilian and Portuguese students. The aspects that explain this differential functioning are related to differential emphases not only on certain mathematics contents but also on the cognitive processes and on the item format.