A sample of patients with endogenous depression (RDC), who had only a partial response to electroconvulsive therapy (ECT), was identified from a larger group of patients participating in a study of the affective and cognitive effects of low-dose titrated ECT. Using symptom scores on the Hamilton Rating Scale for Depression, subscales were constructed to reflect Klein's formulation of endogenomorphic depression, the RDC for endogenous subtype, and the DSM-III criteria for melancholia. Regardless of the subscale used, no evidence was obtained that endogenous symptoms were more responsive to ECT than non-endogenous symptoms.