BACKGROUND: There is growing need for research in China regarding posttest risk behavior differences among injecting drug users that explores the effect of various testing modes (nonvoluntary vs. voluntary) and other related factors on changes in posttest risk behaviors. METHODS: One hundred seventy-two study subjects self-reported human immunodeficiency virus (HIV)-related personal risk behaviors including condom use rates and needle-sharing habits. Fisher exact test and multivariate regression analysis compared the impact of HIV testing mode on ongoing risk behaviors for HIV transmission. RESULTS: The study found that those who received positive test results were 5.37 times more likely to increase condom use with regular sexual partners, that men were 8.8 times more likely than women to increase posttest condom use in commercial sexual activities. Needle-sharing behavior was significantly lower for subjects who tested HIV-positive (odds ratio [OR]: 4.5), who notified sexual partners of test results (OR: 0.03), and who had tested voluntarily (OR: 0.04). CONCLUSION: Based on the study results this report concludes that voluntary HIV testing and encouragement of partner notification of test results should be incorporated into China's national testing strategy.