Objective: Recently, novel psychological treatments for adult ADHD have been reported with promising results. However, studies about long-term treatment effects are scanty. The authors study effects of cognitive-behaviorally-oriented group rehabilitation during a 6-month follow-up. Method: Participating in the rehabilitation were 29 adults, of whom 25 were reached 3 and 6 months later. ADHD and other psychiatric symptoms were assessed with self-ratings (Brown ADD Scale for Adults, Symptom Check List-90 [SCL-90], 16 ADHD-related items of SCL-90, Beck Depression Inventory). Participants from the pretreatment period served as their own controls. Results: Participants having improvement in ADHD symptoms during treatment (n = 11) maintained most of the benefit during follow-up. They also had a decrease in other psychiatric symptoms, but this did not fully persist through the follow-up. Of all participants, 72% found their overall situation improved as compared to the pretreatment situation. Conclusion: Results suggest that cognitive-behaviorally-oriented group rehabilitation of ADHD adults might have long-term benefits. (Contains 2 figures.)