Since the 1990s, we have suggested the concept of pre-alcoholism which encompasses patients who have drunk a great deal of alcohol leading to alcohol related problems such as health issues, domestic violence, drunken driving and black-outs. Pre-alcoholism excludes alcohol-dependent patients who have experienced continuous drinking or withdrawal symptoms. We have treated many outpatients with pre-alcoholism for several years. Our regimen demands that the patients must be abstinent for half a year at the beginning of their treatment. After half a year they can choose whether they will continue to be abstinent or they will resume drinking with the aim of reducing their total alcohol consumption. The study clarified the character of pre-alcoholism by investigation of the patients' background and re-diagnosis of the patients based on the International Classification of Diseases, 10th Revision (ICD-10). A remarkable ratio of pre-alcoholic patients was diagnosed with alcohol dependence under ICD-10. We classified pre-alcoholic patients into two groups, one diagnosed as having ICD-10-classed alcohol dependence and the other which did not fulfill the ICD-10 diagnostic criteria of alcohol dependence, and examined the therapeutic processes of the two groups. It was shown that most pre-alcoholic patients could finally take required courses of treatment by themselves without regard to diagnosis under ICD-10, even if they chose any treatment and made alcohol related mistakes on the way. Our findings suggested that pre-alcoholic patients, a portion of whom may have exhibited mild alcohol dependence, could select drinking reduction as a primary goal of treatment after a certain period of abstinence.