Post-treatment evaluation studies of behaviour therapy (BT) for trichotillomania (TTM) have shown that BT is successful in reducing symptoms in this impulse-control disorder. The present study was aimed at investigating gain maintenance at long-term follow-up. TTM-related symptoms and other symptom characteristics were evaluated in 28 patients suffering from TTM before and after brief BT and at a 3-month and 2-year follow-up. The manual-based BT consisted of self-control procedures offered in six sessions. Pre-post effect sizes for TTM symptoms at post-treatment evaluation and at the two follow-ups were 2.91, 1.47, and .87. Compared to the post-treatment effects, the 3-month and 2-year follow-up effect sizes had decreased by 49% and 70%, respectively. Better 2-year follow-up results were associated with lower pre-treatment levels of depressive symptoms and with complete abstinence from hair pulling immediately after treatment.