Japanese adolescent drinking has increased during the past 20 years. Two national surveys on adolescent drinking problems were conducted, but no prospective study has been performed in Japan. We started the first longitudinal cohort study on Japanese adolescent alcohol use and misuse in 1997. The purpose of the cohort study was to show factors that promote adolescent drinking, and whether adolescent problem drinkers will develop the early alcohol dependence syndrome. Eight hundred and two subjects were recruited from four junior high schools in Kanagawa prefecture. They were in grades 7 to 9, and the mean age was 13.5 years in 1997. The survey was conducted annually by mail using self reported questionnaires concerning adolescent drinking and alcohol-related problems. This report indicates the sociodemographic backgrounds of the subjects and showed increasing of drinking of the subjects from 1997 to 1999. At 1999 survey from 2 years after the starting point, the respondents numbered 629, and the follow-up rate was 78%. Drinking frequencies and quantities of the subjects increased year by year, and alcohol-related problems also increased. We divided the subjects into two groups based on changes in drinking status from the 1997 to the 1999 survey, the increased drinking group and no increased group, and compared these two groups concerning their family relationships, first drinking age and drinking status of parents with the responses of the 1997 survey. In the comparison of the two groups, many factors were significantly different, and logistic regression analyses were performed on these factors to determine drink promoting factors. Three factors were determined: earlier age of the first drink, not refusing friends' temptations to drink and less communication with their parents. We will continue the longitudinal cohort study to determine if these three factors promote adolescent drinking in the future.