OBJECTIVE The aim of this study was to explore the relationship between alexithymia and borderline personality disorder (BPD) in adolescents. METHODS The study investigated a sample of 59 consulting or inpatient adolescents with a well-established diagnosis of BPD (SIDP-IV) and a control sample of healthy adolescents individually matched by gender, age and socio-economic status. Alexithymia, depression and trait-anxiety were rated using the Twenty-item Toronto Alexithymia Scale (TAS-20), the Beck Depression Inventory (BDI-II) and the trait-anxiety subscale from the State-Trait Anxiety Inventory (STAI-T), respectively. A confirmatory factorial analysis (CFA) was performed to test the fit of the three-factor structure of the TAS-20 in the adolescent sample (N=140). BPD and control groups were compared on alexithymic scores using ANCOVA analyses controlling for the potential confounding effects of depression and anxiety. RESULTS The ratio of the chi-square to its degrees of freedom, the goodness-of-fit index, the adjusted goodness-of-fit index and Steiger's root-mean-square error of approximation had satisfactory values of 1.54; 0.87; 0.83 and 0.058, respectively. The two ANCOVA demonstrated no significant difference for TAS-20 scores. BPD subjects were more alexithymic than healthy subjects but this difference was mainly explained by the levels of depression or anxiety. CONCLUSIONS Since BPD subjects have high comorbidity with depression or anxiety, longitudinal studies examining the absolute and relative stability of TAS-20 scores are necessary to determine whether alexithymia constitutes a state or a trait in BPD. CONCLUSIONS BPD adolescents are characterized by alexithymia, probably of a secondary or state-dependent nature.