This study explored the relation of alexithymia (cognitive and affective deficit in processing, adjustment and verbalizing emotions) with interpersonal problems in a sample of adolescents. One hundred seventy-four (174) high-school students completed Toronto Alexithymia Scale (TAS-20) and a short version of Inventory of Interpersonal Problems (IIP-32). As we expected, alexithymia is positively associated with interpersonal problems, high alexitymic adolescents having significantly more interpersonal problems than non alexithymic adolescents. Regression analysis showed that interpersonal problems can be predicted by alexithymia. This study highlights the negative impact of alexithymia on adolescents's relationships, through the interpersonal problems that alexithymia produces in their life.