The study collected data from 326 heroin users in Guangxi Province, China, in 1997. Logistic regression analysis identified risk factors for injection. Survival analysis identified factors independently associated with time from initiation of heroin use to adoption of injection. Four factors were independently associated with injection: number of friends who used heroin in the last year, duration of heroin use, dose of heroin consumed, and total number of times detoxified in drug treatment and rehabilitation centers. Only gender and duration of heroin use were independently associated with time to first injection. Median time to first injection was 11 months for males and 22 months for females. Median time to first injection varied by age. Median time to injection for those who used heroin for more than 1 year was 8.1 months; it was 19.1 months for 1 to 5 years of use, and 40.5 months for more than 5 years of use. The study’s preliminary findings suggest that younger, more recent heroin users and males are at increased risk of becoming injectors, a major risk behavior for HIV acquisition. Tables, figures, references