Abstract: In order to test the possible relationship between the chronic consumption of alcohol and the opioid system, we have measured the plasmalevels of β-endorphin in a group of 31 alcoholic patients and compared the results with those of a control group of 16 subjects. Our results show that chronic consumption of alcohol induces a significant decrease in β-endorphin (β-end) plasmalevels regardless of either the disease suffered by the alcoholic patient or of the time of abstinence studied (one month maximum). Thus we believe that the β-end decrease may well be due to the patients’ alcoholism and that it might be mediated by the tetrahydroisoquinoline system, or be a cause of alcoholism rather than a consequence.