Peer-based models for human immunodeficiency virus (HIV) testing have been implemented to increase access to testing in various settings. However, little is known about the acceptability of peer-delivered testing and counseling among people who inject drugs (IDU). During July and October 2011, data derived from the Mitsampan Community Research Project were used to construct three multivariate logistic regression models identifying factors associated with willingness to receive peer-delivered pre-test counseling, rapid HIV testing, and post-test counseling. Among a total of 348 IDU, 44, 38, and 36 % were willing to receive peer-delivered pre-test counseling, rapid HIV testing, and post-test counseling, respectively. In multivariate analyses, factors associated with willingness to access peer-delivered pre-test counseling included: male gender (adjusted odds ratio (AOR) = 0.48), higher than secondary education (AOR = 1.91), and binge drug use (AOR = 2.29) (all p < 0.05). Factors associated with willingness to access peer-delivered rapid HIV testing included: higher than secondary education (AOR = 2.06), binge drug use (AOR = 2.23), incarceration (AOR = 2.68), avoiding HIV testing (AOR = 0.24), and having been to the Mitsampan Harm Reduction Center (AOR = 1.63) (all p < 0.05). Lastly, binge drug use (AOR = 2.40), incarceration (AOR = 1.94), and avoiding HIV testing (AOR = 0.23) (all p < 0.05) were significantly associated with willingness to access peer-delivered post-test counseling. We found that a substantial proportion of Thai IDU were willing to receive peer-delivered HIV testing and counseling. These findings highlight the potential of peer-delivered testing to complement existing HIV testing programs that serve IDU.