REM latency and rectal and ear canal temperature were studied simultaneously in 11 controls and nine depressed patients; seven of the patients were studied when recovered. REM latency was shorter in the depressed group compared with controls and lengthened with recovery. The nocturnal and ear canal temperatures were higher in the depressed group compared with controls and decreased with recovery. REM latency and the nocturnal rectal temperature were negatively correlated when all the nights of the depressed patients were analyzed (r = -0.44) and when all the nights of the subjects were analyzed (r = -0.44). REM latency and nocturnal ear canal temperatures were negatively correlated when all the nights of the control group were analyzed (r = -0.34). The timing of the temperature rhythm did not appear to be correlated with the REM latency.