Objective: Hepatitis C virus (HCV) incidence has been increasing among young injection drug users (IDUs). This analysis examined whether the emerging practice of prescription opioid (PO) injection is associated with self-reported HCV among young IDUs. Methods: Young IDUs (n = 162) aged 18-25-years-old who indicated recent misuse of prescription drugs were sampled in New York and Los Angeles during 2009--2011. Participants reported lifetime PO injection history and results from their most recent HCV test as well as demographic characteristics and lifetime drug use. Bivariate analyses examined relationships between covariates and both lifetime PO injection and HCV positivity. Poisson regression examined the associations between lifetime PO injection, HCV positivity, and significant covariates. Results: A majority reported lifetime PO injection (72.2%) and 30.9% self-reported being HCV positive. Lifetime PO injectors were nearly three times more likely to report being HCV positive than non-PO injectors (adjusted incidence rate ratio (AIRR): 2.69, p < 0.05) after controlling for socio-demographic and other drug use variable. Additionally, substituting POs for heroin (AIRR: 2.27, p < 0.05), growing up in a lower social class (AIRR: 1.67, p < 0.05), age (AIRR: 1.12, p < 0.05), age of injection initiation (AIRR: 0.87, p < 0.001), and history of being prescribed stimulants (AIRR: 0.64, p < 0.05) were independently associated with HCV positivity. Conclusions: Findings suggest that PO injection should be given further consideration as a contributing factor to rising HCV infection among young adults in the US.