Efforts to elucidate the abnormal mechanism of corticotropin and beta-endorphin in major depression have yielded conflicting findings. The relationship of plasma levels of cortisol, corticotropin, and beta-endorphin in 42 patients with a Research Diagnostic Criteria diagnosis of major depression, endogenous subtype was examined. Following the DST, 32 patients were nonsuppressors and 10 were suppressors. The differences between the median values for plasma corticotropin and beta-endorphin immunoreactivity were not significant at any time of measurement after the DST.