The aim of this study was to examine moderating effect of attachment styles on the relationship between alexithymia and interpersonal problems in a sample of students. Four hundred and fourty three high school students (213 boys, 230 girls) from the city of Tehran schools participated in this study. All participants were asked to complete Adult Attachment Inventory (AAI), Farsi version of the Toronto Alexithymia Scale (FTAS-20), and Inventory of Interpersonal Problems (IIP-60). Results revealed a significant negative correlation between secure attachment style and interpersonal problems. Avoidant and ambivalent attachment styles and alexithymia showed a significant positive association with interpersonal problems. Analysis of the data revealed that the relationship between alexithymia and interpersonal problems was moderated by attachment styles. It can be concluded that secure and insecure attachment styles moderate the relationship between alexithymia and interpersonal problems in opposite directions.