Objectives: The study was designed to assess the trends of the incidence of HIV among young people and their sexual risk-taking behaviors by gender in Korean college students. Methods: The cross-sectional study was used from college students from selected 60 among 208 4-year colleges and universities in 9 provinces and Seoul. A self-reported anonymous questionnaire administered and completed to a national representative sample of 4-year college students from May 15th to June 14th in 2003. We analyzed 2,385 cases. The overall response rate was 82.0%. Results: After controlling age effects, male students were more likely to be sexually experienced than female students(40.0% vs. 8.1%), OR=5.5, p<.000. The proportions of 19 years and before reported for initiation of sexual intercourse were 18.6% for males and 3.2% for females. Males reported significantly younger ages than females at initiation of sexual intercourse(p<.01). Only 14.8% of current sexually active subjects reported consistent use of contraceptive methods. After controlling age effects, male students reported a higher proportion of sexually experienced respondents with one or more casual partners(excluding a formal partner) during the last 12 months than women(38.8% vs. 22.2%), OR=2.2, p<. 05. Conclusion : This study can conclude that although males students initiate sex earlier and have higher percentage of sexual experience, the percentage of sexually experience female students has risen rapidly compared to the past. This data revealed a number of young people were at risk for HIV infection. Both genders are equally likely to have engaged in inconsistent condom use even though when they have a sex with an unknown partner. These findings suggest that practical sex education focused on using condom use should have been included in the school curricular. Educational and community interventions need to prevent sex-related problems.