The purpose of the present 6-week multicenter dose finding study was to compare the efficacy and tolerability of mirtazapine (preferentially presynaptic alpha 2-adrenergic receptor blocker) to placebo in hospitalized patients with major depression. The clinical efficacy was evaluated with the Hamilton Depression Scale (HAM-D), Montgomery-Asberg Depression Rating Scale (MADRS), Beck Self-Rating Depression Scale, Global Assessment Scale (GAS), and Brief Psychiatric Rating Scale (BPRS). The side effects were recorded on a checklist of emergent symptoms (ROSE) and physical examinations, ECG, clinical chemistry, and hematology tests were carried out. The dosages of mirtazapine were gradually raised from 15 mg to 50 mg. One hundred and fourteen patients were included. Twenty-two patients (37%) in mirtazapine group and 24 (44%) in the placebo group were prematurely withdrawn from the study mainly due to inadequate efficacy. The decrease in HAM-D and MADRS was generally more pronounced in the mirtazapine group than in the placebo group. Minor side effects were reported in less than 15% of the patients in both groups. Only fatigue and faintness were slightly more pronounced in the mirtazapine group than in the placebo group. No significant changes were found in laboratory parameters. Because of methodological flaws like combining a dose finding study with a placebo controlled study, further conclusions should not be made on the efficacy of mirtazapine when treating depressive patients.