This paper exploits the discrete jump in alcohol consumption at the minimum legal drinking age (MLDA) in the USA and uses a regression discontinuity design to investigate the relationship between drinking and risky sexual behaviors among young adults. Using confidential data from the National Longitudinal Survey of Youth (1997 Cohort), we document that young adults tend to drink up to 2.1 days more once they are granted legal access to alcohol at age 21. Although the discrete jump in alcohol consumption at the MLDA is associated with an increase in the probability of having sex by up to 7.8 percentage points, it does not have a significant impact on the probability of engaging in risky sexual behaviors among young adults. We also document that the effect of the MLDA on the probability of using several different birth control methods is not significant for those who had sex in the past 4 weeks. These results are robust under alternative specifications and imply that although the MLDA law is quite effective in reducing alcohol consumption among young adults, spillover effects of this law on risky sexual behaviors are relatively limited.