Safety aspects [adverse events, blood pressure and heart rate, weight, and laboratory tests (liver parameters, hemoglobin, leukocytes)] of long-term treatment in 1,120 patients are discussed. Adverse events during this long-term treatment were also compared with those of a subgroup of these patients who, before long-term treatment, were treated on a short-term basis (n = 706). Efficacy [Hamilton Depression Rating Scale (HAM-D), Clinical Global Impression of Efficacy (CGI), and occurrence of relapses and recurrences] in a homogeneous sample of 485 patients is also discussed. The adverse events most frequently observed during long-term treatment were insomnia, headache, and dizziness. Insomnia and headache were also most often occurring in the compared sample of patients with short-term treatment, whereas dizziness during this treatment period ranked at the fifth position. Supine and standing mean blood pressure did not consistently change during long-term treatment, the most prominent increases in comparison with baseline were seen in the period > 1 year of treatment (6.3 mm Hg supine/7.2 mm Hg standing). Comparison of blood pressure values in the hypertensive range at baseline and during long-term treatment revealed no statistical difference (McNemar test p = 0.07829). Mean heart rate slightly decreased during long-term treatment (by a maximum of 6.3 beats/min supine, 8.2 beats/min standing). Mean weight did not change between baseline and treatment end point. There were 23 patients with a weight loss of 10 kg or more and 16 patients with a weight gain of 10 kg or more. For none of the laboratory parameters tested was there a statistical significance regarding shifts from normal to pathological values. HAM-D mean total scores in the above-mentioned subgroup of patients decreased from 25.05 points at baseline (n = 485) to 7.88 points after 1 year of treatment (n = 139). Seventy-five patients who had favorably responded to treatment (total responders n = 300) relapsed during the first 6 months of treatment. During the second half-year of treatment the recurrence rate was 14.8%, and during the third 6 months the recurrence rate was 12.2%. CGI in the same subsample of patients in whom HAMD was evaluated (n = 485) compared with those patients who did not drop out during the short-term period up to 44 days and entered long-term treatment (n = 401) showed that the percentage of the ratings “no change/worse” was higher in the sample that also included patients who withdrew from treatment during the short-term period. Comparison of the total of patients with long-term treatment (n = 1,120) and the previously mentioned subgroup with long-term treatment (n = 401) showed that in the larger sample, ratings of “very good” were more frequent and that the percentage of ratings “no change or worse” was lower. From the present results it may be concluded that moclobemide is safe during long-term treatment and that efficacy—according to mean HAM-D total scores and CGI of efficacy tested in selected samples—seems even to improve during long-term treatment. The relapse and recurrence rates were comparable to those published for other antidepressants.