A study of 109 chronic, post-traumatic stress disorder patients found 65 suffered current major affective disorders. Of these 65, 84.8% had major depression and 15.2% had bipolar disorder. Nonsuppression of the DST occurred only in those cases with concurrent major affective disorder, the incidence of nonsuppression was 32.3%. Treatment effectively attained clinical improvement and conversion of nonsuppressor to suppressor state in these cases. The DST, cortisol suppression index, and inhibition of cortisol production index were useful to support the clinical diagnosis of major affective disorders in post-traumatic stress disorder patients, in an exclusively clinical setting.