Infection drug use is the second most common HIV risk behavior in the United States, but little is known about injection drug use and needle-sharing behavior among street youth, a group at high risk for HIV infection. This study investigates the drug use histories, injection drug use behaviors, and needle-sharing practices of 106 injection drug using youth in Los Angeles, California. Respondents report high rates of injection drug use and needle sharing, indicating that these youth are at particularly high risk for HIV infection. Results suggest a need for outreach services tailored to the unique needs of injection drug-using adolescents.