The effect of cognitive behavioural therapy (CBT) is well-documented for individual interventions for depression. Studies of group interventions for depression using CBT principles are more sparse. Hence the reason for this naturalistic study that reviews the results of a short term 12-session manualized CBT group intervention offered in an inpatient setting at the Specialized Treatment Unit for Depression and Anxiety at the Psychiatric Centre Copenhagen, Bispebjerg Hospital, over a 5-year period. The aim of the study was the treatment and relapse prevention of depressive symptoms by teaching patients cognitive behavioural therapeutic methods. The manual deviated only slightly from Melanie Fennell's treatment model. Sixty-two patients were referred and 48 participated, 45 of these had been inpatients with moderate to severe major depression admitted to the ward with a depressive episode or recurrent depressive episodes of at least 2 weeks and up to 2 years’ duration. So far the results are promising, measured by the decrease in the Beck Depression Inventory (BDI-II) score at session 12 [mean BDI-II score at baseline: 30.7 (s.d. = 9.9); post-treatment: 20.4 (s.d. = 12.6), p<0.0001], relapse was measured by the rate of readmissions compared to data published in a previous register-based study on Danish patients with unipolar depression, which showed significantly lower rates of readmission in our sample (p = 0.003) and patients’ self-reported improvement, indicating that treatment in groups can be recommended, although a 12-session programme may have to be extended for people with more complex and longstanding personality impairments and recurring depression. Secondary gains not originally intended, but pointed out in patient feedback, were the strengthening of social skills and self-esteem.