• Fifty-one newly hospitalized depressed patients participated in a double-blind comparison of two dosage levels of imipramine hydrochloride (150 mg vs 300 mg daily). Although some patients were suffering from neurotic depressions, they, together with the endogenous depressives, were a severely depressed group who required hospitalization. Improvement occurred with both dosage regimens, although a greater and more consistent improvement was noted in the 300-mg group than in the 150-mg group. There were a few differences between the response of the endogenous and that of the neurotic depressives, as assessed by the physician and self-rating scales. However, endogenous depressives who received 150 mg were overrepresented in the treatment failure group. A comparison of the response of deluded and nondeluded depressives indicated that the deluded patients responded less well than the nondeluded depressives, although half of the delusional group did respond to the treatment.