Although alcohol use has been associated with risky behavior generally, the relationship between alcohol use and multiple types of risk behaviors that could lead to the acquisition and transmission of HIV and hepatitis C (HCV) among people who inject drugs (PWID) has not been fully examined. The current study seeks to contribute to the understanding of how alcohol use is related to both injection risk and sexual risk, among a non-treatment, cross-sectional sample of mostly male PWID in rural Puerto Rico (n=315). "At-risk" alcohol use was defined as consuming ≥14 drinks per week for males and ≥7 drinks per week for females. Binge drinking frequency was defined as consuming ≥5 drinks on one occasion for males and ≥4 drinks on a single occasion for females. Multivariate regression models were used to examine the association between the alcohol use variables and injection and sexual risk outcomes, adjusting for demographic characteristics. Overall, 14% (n=45) of the participants in this sample were considered at-risk drinkers (44% low risk drinkers and 42% alcohol abstainers), and participants reported binge drinking, on average, at least once per month. At-risk drinking, compared to low risk or no drinking, increased both injection and sexual risk behaviors. Frequency of past year binge drinking was also associated with both injection and sexual risk behaviors. Interventions aimed at reducing HIV and HCV transmission among injection drug users non-PWID networks should both target individuals who drink alcohol frequently and in high volumes, and include strategies for reducing risky behaviors while heavy drinking is occurring.