Background: The aim was to examine the role of alexithymia on therapeutic outcome in a naturalistic group therapy setting, as well as the effectiveness of cognitive-behavioural group therapy in reducing alexithymia. Methods: A pre-test/post-test research design was used to examine alexithymia before and after treatment. Pre- and post-alexithymia and psychological distress scores from routinely administered measures were retrieved for 61 psychiatric outpatients referred for group therapy at a mental health facility. Correlation, repeated measures t-test, and regression analyses were conducted to explore the data. Results: Baseline alexithymia was not a significant predictor of group therapy outcome (change in psychological distress) once baseline psychological distress was controlled for. There was a small but significant reduction in mean-level alexithymia scores over the course of therapy. A high level of relative stability was observed in alexithymia scores, independent of change in psychological distress severity. A reduction in alexithymia during treatment was a significant predictor of a reduction in psychological distress over the course of therapy. Conclusions: High baseline alexithymia does not present a therapeutic disadvantage for patients receiving cognitive-behavioural group therapy. However, cognitive-behavioural group therapy is somewhat effective at improving alexithymic features, and this improvement can provide symptom relief by the end of treatment. Thus, it may advantageous for clinicians to treat alexithymia in order to enhance therapeutic intervention.