In a retrospective study, the drug response of delusional patients with primary depression who were treated with tricyclic antidepressants (TCA), neuroleptics, or combined TCA plus neuroleptic therapy was examined. Significantly more patients responded to the combined drug regimen, as has been found in other recent studies. Clinical response was not related to severity of symptoms, drug dosage, or demographic characteristics. The clinical superiority of neuroleptics plus TCA in the treatment of delusionally depressed patients suggests the possible role of dopamine in the psychosis associated with depression and implicates norepinephrine and serotonin in the disordered locomotor activity and mood of primary depressive illness.