This research was conducted in order to determine whether math anxiety was effective in the selection of secondary school students. This research, in which the mixed method was adopted, was conducted in a secondary school at Siirt. The participants (157 pupils) were determined by convenient sampling method from the four different classes (two 5th grade and two 8th grade). Math anxiety levels of the students were determined by the Mathematics Anxiety Scale. Sociometry technique was used to determine the informal friends groups in each class. For this purpose, a friend preference form was used. Students' friends preferences were transformed into data matrix and Hierarchical Clustering Analysis was used to form informal friends groups for each class. Math anxiety scores of informal groups were compared with Kruskal Wallis test. Accordingly, there were significant differences between the mathematical scores of the informal groups in the branches of the 5th and 8th grades. This finding was evaluated that mathematics anxiety may be a factor in the selection of friends.