Baseline plasma levels of beta-endorphin, beta-lipotropin, and ACTH were assayed in 37 patients with chronic schizophrenia: 24 men and 13 women, 28 with hebephrenic and nine with paranoid schizophrenia. None of the patients had received any medication for at least 10 days. The mean values of both opioids were significantly higher in the schizophrenic patients than in 21 age- and sex-matched control subjects. Insulin stimulation and dexamethasone suppression tests were given to eight of the patients, and the circadian rhythms of beta-endorphin, beta-lipotropin, ACTH, and cortisol were assayed in the same eight patients. Insulin stimulation, dexamethasone suppression test results, or circadian rhythmicity was impaired in seven of these eight patients.