About twenty-five years ago thymoleptics made their first appearance which were soon followed by a great number of pharmacological agents that allied a mood elevating activity to an anxiolytic effect. Mianserin, a novel tetracyclic antidepressant, has an antidepressive effect similar to that of its predecessors but without causing the following side-effects : dry mouth, constipation, intestinal atony, tachycardia, cardiac rhythm disorders, accommodation difficulties, intra-ocular hypertension, dizziness, bladder atony and urinary retention. Consquently, its use is particularly indicated for the treatment of those patients who did not react to other antidepressants of those who stopped treatment on account of side-effects. Mianserin may also be used with those patients suffering from glaucoma, urinary or prostatic disorders and cardiac disorders even when the patient is recovering from a recent heart infarction. Furthermore it is recommended for aged people, for patients in a bad general condition and for those who were in a confusioned state during treatment with tricyclic antidepressants.