Objectives : It is well-known that Korean people show distinctive drinking behaviors depending on the gene polymorphisms of alcohol metabolizing enzymes. This study examined the gene polymorphisms of ALDH2 and ADH1B and their combination on the drinking behaviors of Korean young adults. Methods : Through a follow-up survey performed for a cohort consisting of 551 university freshmen for six years, the authors attempted to identify genetic factors affecting drinking behaviors. In 2000, drinking behaviors and scores of CAGE questionnaires were assessed and ALDH2 gene polymorphism was determined with PCR-RFLP. In 2006(n= 150), AUDIT-K was assessed in addition to the above and gene polymorphism of ADH1B was determined through SNaPshot$^{TM}$ method. Results : While ALDH2*2 allele was associated with increased degree of drinking in 2000 and 2006. When both enzymes were active, the possibility to be classified into the risk group for alcohol dependence such as AUDIT-K(>12), and CAGE(>2) was high. Conclusion : The ALDH2 genotype had a significant effect on drinking behavior and degree of drinking during early adulthood. However, the combination of the active form of ADH1B and the active form of ALDH2 can be risk factor for problem drinking.