The thyrotropine releasing hormone (TRH) test and the dexamethasone suppression test (DST) have been carried out in 100 depressive patients, divided into two DSM-III categories: (1) minor depression (dysthymic disorder, 300.40; atypical depression, 296.82; adaption disorder with depressive mood, 309.000); (2) major depression (296.X0, 296.X2, 296.X3, 296.X4). The results show that the two diagnostic categories are significantly (p = 0.0000) discriminated by the results of both tests. The DST has more discriminating power as compared to the TRH-test. The DST and a mathematical weighted sum of both test results in a discriminant score can be used as a predictive diagnostic criterion to separate the major from the minor depression. Half of the patients with major depression are classified correctly with a specificity of 94.7% resp. 97.4% in the case of the DST resp. the discriminant score. A negative test result has no clinical relevance.