Out of 24 patients with endogenous depression, 21 completed the treatment with nortriptyline 150 mg as once-a-day dosage. The therapeutic effect was good and at any rate not inferior to that of dosages several times a day. Side effects were only little pronounced and at any rate not more marked than after dosages several times a day. Out of regard for the administrative and psychological advantages of the once-a-day dosage this form should be preferred, not least in the out-patient treatment with nortriptyline of endogenous depression.