Plasma cyclic-AMP responses to adrenergic agonists are due to stimulation of the peripheral beta-adrenergic receptor. Mood responses to stimulants are thought to be due to actions leading to stimulation of central catecholamine receptors. To determine if a peripheral measure of receptor sensitivity could predict central mood effects of stimulants, the plasma cyclic-AMP response and the mood response to intravenous methylphenidate were determined simultaneously in 13 subjects. No correlation between the two responses was found.