The authors review over 50 reports comparing test sensitivity of the thyrotropin-releasing hormone (TRH) stimulation test using either DSM-III or Research Diagnostic Criteria (RDC) criteria for depression. Ten reports with a total of 410 patients and 458 test results were analyzed that met specific criteria for diagnosis for the TRH test. The sensitivity for depression with the TRH test in the DSM-III reports was 34.8% compared with six RDC reports in which the sensitivity was 51% (chi 2 10.41, p less than 0.001). The authors discuss possible endocrine and psychiatric implications of this finding and encourage researchers to use two methods for diagnosis in future clinical research in order that this type of comparison can be undertaken in the same patients. This will help in future modifications and revisions of the DSM.