Monoamine oxidase inhibitors (MAOI) are a class of drugs which are capable of totally suppressing REM sleep. The MAOI phenelzine was given to six anxious-depressed patients while daily behavioral and EEG sleep records were made. REM sleep was completely suppressed for from 14 to 40 nights. Upon discontinuation of MAOI REM sleep increased as much as 250% above normal levels. The bipolar EEG changes were paralleled by similar changes in depression and anxiety. The behavior of all six patients markedly improved at times when REM sleep was completely absent. Two of the four patients studied after MAOI discontinuation became profoundly anxious with REM compensation. The morning recall of dreams also closely paralleled the presence or absence of REM sleep. Evidence from this study and others indicate that suppression of REM sleep might help to alleviate depression.