The aim of the study was to explore same-sex and opposite-sex friendship functions among 12 to 13- and 16 to 17-year-old Hungarian adolescents (n = 304). To explore perceptions of friendship functions, the McGill Friendship Questionnaire (MFQ, 30 items, 6 factors: stimulating companionship, help, intimacy, reliable alliance, self-validation, emotional security) was used. The confirmatory factor analysis did not support the theoretical structure of MFQ. Based on the exploratory factor analysis, the 26-item Hungarian version of MFQ can be used to measure adolescents (the original 6 factors were retained). The internal reliability indices of the MFQ versions (same and opposite sex) were adequate (Cronbach's [alpha]: 0.69-0.88). The results only partially confirmed the age and gender hypotheses. Based on the results, the older students are more likely to acknowledge the achievements and positives of a friend for both same-sex and opposite-sex friends, as well as intimacy for opposite-sex friends. Also among older students, we identified several significant gender differences: for girls, all features of friendship were more important, except self-validation in same-sex friendship. In the opposite-sex relationship, only stimulating companionship and reliable alliance are more important for girls. The results raise the possibility that friendship functions build on and reinforce each other with age.