The drug abusers in Ho Chi Minh City were older, more likely to be employed, and less likely to be single than were those in Hanoi. Their histories of injecting also varied. On average, the participants in Ho Chi Minh City had been injecting for 17 years, compared with 3 years in Hanoi. Three-quarters of the participants injected at least once a day; a similar proportion had their injections administered by someone else. Eighty-two percent had seen something, read something, or both regarding HIV and AIDS; 73 percent mentioned having initiated risk reduction. However, no significant difference existed between the two cities; the participants in both cities continued to expose themselves to HIV infection. In addition, the participants in the two cities did not differ with respect to initiating HIV risk reduction, although prevention programs began in Ho Chi Minh City earlier than in Hanoi. The presence of high-risk behaviors and the absence of any meaningful risk reduction among injecting drug users in both cities indicated the need for intensive targeted intervention. Tables and 4 references (Author abstract modified)