Purpose: This study was performed to determine the effect of drinking prevention program on the levels of drinking related knowledge, attitude, drinking refusal self-efficacy and behavior of vocational high school girls. Methods: Pre-post test design. The subject was used for a group of high school girls. The data were collected on May and September, 2006 and June, 2007 and analyzed using paired t-test. Results: The drinking-related knowledge score after one year was significantly higher than that of pretest (t=-14.02, p=.001) and the drinking-related attitude score was lower (t=2.85, p=.006). The drinking refusal self-efficacy and the drinking behavior measured as number of drinking events, amount of alcohol and number of heavy drinking events were not significantly different between pretest and post test after one year. Conclusion: Drinking prevention program should be given to increase the drinking refusal self-efficacy and decrease or prevent the drinking behavior of high school girls every semester at least.