The purpose of the article is to investigate how countries can be grouped according to their students’ mathematics achievements. The patterns of students’ answers for groups of countries are searched for, based on the difficulty of mathematics items for the students in those countries. The attempt is made not only to group countries according to their mathematics profile, but also to see whether the similarities within the particular group remain throughout the years. The main methods of the research include hierarchical cluster analysis and factor analysis. TIMSS (Trends in Mathematics and Science Study) 1995 and 2003 data is used for the analysis. Mathematics results of Grade 8 students of all participating countries are included. The investigation shows that although essentially the same groups remain throughout the three TIMSS cycles, but at the same time there are several interesting changes and the mathematics profile of all participating countries in the survey becomes more similar to each other.