Maprotiline (Ludiomil) is a dibenzo bicyclooctadiene pharmacologically related to the tricyclic antidepressants and stereochemically having a tetracyclic structure. A controlled, double-blind comparison of maprotiline and imipramine in a group of 71 female outpatients with primary depression is presented. Maprotiline was found to be at least as effective as imipramine and significantly better in depressive neurosis. It also showed a bipolar action, being effective in both agitation and retardation.