Objectives: This study is to develop a web-based prevention program of alcohol-related problem among university students and to examine its efficacy in changing drinking behaviors and reducing harms associated with alcohol use. Methods: An hour-length program was developed containing news paper articles, pictures, stories and questionnaires in a multimedia format such as flash, animation, and text. Survey data were analyzed to examine program efficacy from a convenient sample of 1,080 freshmen enrolled in a participating university. Results: Participation in the program has resulted in statistically significant changes in drinking behavior between pretest and follow-up, including reduction of frequency of drinking, heavy drinking, and intoxication, typical amount of drinking per occasion, and subjective norm of heavy drinking. Repeated ANOVA revealed significant increases in knowledge on alcohol related facts, including recommended drinking unit by WHO with substantial level of effect size and in making negative alcohol expectancy with very low effect size. Further studies are guaranteed with randomized controlled trial for the program effectiveness. Conclusions: A web-based prevention program of alcohol-related problems in this study was efficacious in changing drinking behavior, knowledge on alcohol-related fact, alcohol expectancy and subjective drinking norm.