In this study, we examined the possible role of acetaldehyde in the mediation of the reinforcing properties of ethanol. We also examined the possible interaction of acetaldehyde and brain norepinephrine in this mediation. We found that rats will self-administer acetaldehyde delivered into the cerebral ventricles, and that this operant behaviour can be attenuated by injections of a dopamine-beta-hydroxylase inhibitor. The results are discussed in terms of a role for tetrahydroisoquinoline alkaloids in alcoholism.