Pirandamine is the potential antidepressant drug. It is a relatively selective inhibitor of the serotonin uptake mechanism and does not exhibit appreciable norepinephrine uptake blocking activity in contrast to the tricyclic antidepressant drugs imipramine and amitriptyline. Pirandamine is equivalent to amitriptyline and greater than imipramine in potency as a serotonin uptake blocker and a potentiator of central serotonin pharmacological actions, and in contrast, does not exhibit appreciable central anticholinergic effects. Pirandamine potentiated the behavioral effects of 5-hydroxytryptophan in mice. Pirandamine, in contrast to desimipramine and imipramine, did not prevent reserpine-induced hypothermia. The (-)-enantiomer of pirandamine retained the activity of the racemate; the (+I-enantiomer was much less effective.