Covariance of brain electrical activity (EEG), plasma adrenocorticotrophic hormone (ACTH) and cortisol levels, and mood states were determined for healthy adult men during the first 2 hr after ingestion of ethanol or ethanol placebo under controlled double-blind conditions. Analysis of integrated plasma ACTH and cortisol levels at 5-min intervals, EEG power spectral analysis during consecutive 2-min epochs, and continuous assessment of mood states with a nonverbal instrumental device were carried out during the ascending phase of the blood ethanol curve. Ethanol induced rapid changes in brain electrical activity and plasma ACTH levels that were significantly correlated with subjective perception of changes in mood. The paroxysmal short epochs of euphoria associated with electroencephalographic and ACTH responses during the ascending phase of the blood ethanol curve may reflect physiological concomitants of pharmacological and behavioral reinforcers that enhance risk for perpetuation of drinking and alcohol abuse.