Heroin and other opiates accounted for 77 percent of all admissions that involved the use of drugs through injection. The other most commonly reported injected drugs were stimulants (16 percent) and cocaine (6 percent). The number of admissions for any injection drug use increased 18 percent between 1992 and 2003, while admissions that did not involve injection increased by 20 percent. Although opiates were the most commonly reported injected substance for all racial/ethnic groups, Hispanics and Blacks reported the highest percentages (92 percent and 90 percent, respectively). The racial/ethnic groups that reported stimulant injection were most often American Indians/Alaska Natives (38 percent) and Whites (21 percent). Frequency of use in 2003 was highest among admissions for injected opiates. Injection drug admissions tended to have used drugs for many years before entering the treatment system. Injection drug admissions often had a history of repeated treatment. Overall, 24 percent of all injection drug admissions reported five or more treatment episodes, compared to 8 percent for all other admissions. Injection of more than one type of drug was reported for 19 percent of injection drug admissions in 2003. There were distinct regional differences in the drug injected. 1 table and 2 figures