Both oral and intravenous TRH produce systematic alterations in brain function of depressive patients as determined by scalp-recorded computerized cerebral biopotentials (computer EEG). The computer EEG (CEEG) profiles of both formulations are not only very similar to each other, but also resemble the CEEG profiles of psychostimulant compounds (Bio-availability). As in CEEG findings, TSH plasma levels also indicate that oral TRH is indeed an active compound. Although some "antidepressive" effects were observed after both formulations, they were not present in every patient, and it was not always the case after repetitive TRH administration, nor were the effects on depressed mood too impressive. On the other hand, in almost all patients certain behavioral effects of TRH were seen which related to "life instincts" and "life performance". The increase of interest, desire and drive for work, food and sex was one of the most striking findings, particularly after intravenous TRH. This may be responsible for the "antidepressive" effects of TRH in patients in whom depression may be the result of an inhibition of "instinctive" functions.