Ethanol has had a long and deep association with the historical development of world culture. Ostensibly, its consumption has both short and long term positive and negative effects, based on moderate or excessive intake, respectively. The predominant thrust of empirical research, however, into the multiple biological effects of ethanol has led to its negative designation as a major addictive substance. Multiple lines of research have elucidated functional interactions of ethanol in opioid modulation of dopaminergic transmission in CNS reward systems. In parallel, recent work has demonstrated that animal cells have the ability to effect de novo synthesis of chemically authentic morphine from dopamine (DA) and DA-related aromatic precursor molecules. Interestingly, we have observed that sub-threshold concentrations of ethanol alter cellular distributions of endogenously expressed morphine. Reciprocal autocrine/paracrine modulatory effects of very low concentrations of morphine in concert with ethanol also suggest the potential for endogenous expression and action of homeopathic concentrations of ethanol within discrete cellular microdomains. Perturbation of this subtle regulatory relationship by exogenous intake of ethanol may shed light on the biochemical and molecular bases of reward and addictive states.