Since the late 1980s, incidence of human immunodeficiency virus infection (HIV) has declined 80% among injecting-drug users (IDUs) in the United States; in 2006, an estimated 6,600 (12%) of new HIV infections occurred among IDUs. To assess HIV-associated behaviors among IDUs at risk for HIV infection, CDC analyzed data from the National HIV Behavioral Surveillance System (NHBS) collected during May 2005--February 2006 (the most recent data available). The results of that analysis indicated that, during that period, 31.8% of participating IDUs reported sharing syringes, and 62.6% had unprotected vaginal sex; 71.5% had been tested for HIV, and 27.4% had participated in an HIV behavioral intervention. These data can help guide local, state, and national prevention services tailored to IDUs at risk for HIV infection and other bloodborne or sexually transmitted infections.