Seventy-six patients hospitalized during the course of one year with a depressive episode and without prior history of other psychiatric illness were evaluated retrospectively using the primary affective disorder criteria. Symptom ratings were made by two raters uninvolved in the treatment of the patient and blind to the discharge diagnosis, hospital course, and treatment response. The patients were designated "endogenous" or reactive" based on whether the depressive syndrome was autonomous or responsive to environmental changes. Ninety-two percent of the patients with endogenous depression and 45% of those with reactive depression met the criteria for definite primary affective disorder. We suggest that the primary affective disorder criteria define a heterogeneous group of patients with respect to the endogenous-reactive distinction. The value of criteria that would identify a homogeneous group with an endogenous depressive state is discussed. The primary affective disorder symptoms that did identify patients with endogenous depression were psychomotor change, self-reproach, and decreased concentration.