Mirtazapine is a new antidepressant with a specific pharmacological profile which is different from all other currently available antidepressants. It is a so-called noradrenergic and specific serotonergic antidepressant (NaSSA). 46 in-patients were treated with mirtazapine. The mean dose was 56 mg mirtazapine per day (SD: 23; range: 15 to 90). The duration of treatment was 3.6 weeks (SD +/- 3.4). Patients presented with following diagnosis: 29 (= 63%) were diagnosed as having a unipolar depression, 26% (n = 12) suffered from a depression in the course of a bipolar disorder. 37% (n = 17) were moderately depressed, 52% (n = 24) were severely depressed. 2 patients (= 4%) met ICD-10 (international Classification of Diseases) criteria for a schizoaffective disorder, 2 patients (= 4%) suffered from dysthymia. 1 patient suffered from an organic depressive disorder. The efficacy of the treatment was evaluated with CGI (Clinical Global Impression), when patients were discharged from hospital. 68% of the patients were in partial or full remission (CGI 2, 3 and 4), 17% were unimproved (CGI 5 and 6), in 15% of the patients the treatment was stopped before. Our observations are indicative that mirtazapine is effective in the treatment of moderately and severely depressed patients and therefore confirm the data obtained in phase III-trials. Furthermore we found mirtazapine in either mono- or combination-therapy with various other antidepressants to be tolerated well. Side effects did not cause in a single patient a discontinuation in treatment.