Socías ME, et al. – This study sought to assess patterns of transmitted drug resistance (TDR) and virological response to first–line antiretroviral therapy (ART) among human immunodeficiency virus–infected people who use illicit drugs (PWUD) in a Canadian setting. Between 1996 and 2015, there appeared a significant increase in TDR prevalence among PWUD in Vancouver. Higher risk of virological failure among PWUD with TDR could be explained by some inappropriate ART prescribing, as well as undetected minority resistant variants in participants with chronic HIV infection. Authors suggest testing baseline resistance early in the course of HIV infection to guide ART selection among PWUD in the setting.