['Injection drug users (IDUs) are at risk of acquiring HIV through injection and sexual practices.', 'We analyzed data collected in five U.S. cities between 2002 and 2004 to identify correlates of HIV infection among 3285 IDUs ages 15-30 years.', 'Overall, HIV prevalence was 2.8% (95% CI 2.3-3.4), ranging from 0.8% in Chicago to 6.3% in Los Angeles. Mean age was 24 years, 70% were male, 64% non-Hispanic (NH) white, 7% NH black, 17% Hispanic, and 12% were other/mixed race. HIV infection was independently associated with: race/ethnicity (NH black [AOR 4.1, 95% CI 1.9-9.1], Hispanic [AOR 3.6, 95% CI 1.5-8.4], or other/mixed [AOR 2.3, 95% CI 1.1-5.2] vs. NH white); males who only had sex with males compared to males who only had sex with females (AOR 15.3, 95% CI 6.8-34.5); injecting methamphetamine alone or with heroin compared to heroin only (AOR 4.0, 95% CI 1.7-9.7); reporting inconsistent means of obtaining income compared to regular jobs (AOR 2.3, 95% CI 1.1-4.8); and having a history of exchanging sex for money/drugs (AOR 2.8, 95% CI 1.5-5.2).'] Do young adult injection drug users in the United States continue to practice HIV risk behaviors?