Few studies examine the effectiveness of treatments for opioid use disorder (OUD) among Black individuals despite recent evidence suggesting opioid overdose death rates are, in some cases, highest and increasing at a faster rate among Black people compared to other racial/ethnic groups. This secondary analysis study investigated treatment preference, retention, and relapse rates amongst a subgroup of 73 Black participants with OUD (81% male, mean age 39.05, SD = 11.80) participating in a 24-week multisite randomized clinical trial (“X:BOT”) comparing the effectiveness of extended-release naltrexone (XR-NTX) and sublingual buprenorphine-naloxone (BUP-NX) between 2014 and 2017. Chi-square analyses were used to investigate treatment preference assessed at baseline, and logistic regression analyses were used to investigate differences in the odds of retention and relapse assessed over the 24-week course of treatment between treatment groups. Our findings suggest no differences in preference for XR-NTX versus BUP-NX. However, similar to the parent trial, there was an induction hurdle such that only 59.5% of those randomized to XR-NTX successfully initiated medication compared to 91.6% of those randomized to BUP-NX (OR = 0.13, 95% CI = 0.04, 0.52). No significant differences were found in treatment retention (intention-to-treat: OR = 1.19, 95% CI = 0.43, 3.28; per-protocol [i.e., those who initiated medication]: OR = 0.60, 95% CI = 0.20, 1.82) or relapse rates between treatment groups (intention-to-treat: OR = 1.53, 95% CI = 0.57, 4.13; per-protocol: OR = 0.69, 95% CI = 0.23, 2.06). Although there is a significant initiation hurdle with XR-NTX, once inducted, both medications appear similar in effectiveness, but as in the main study, dropout rates were high. Future research is needed on how to improve adherence.Copyright © 2020 Elsevier Ltd. All rights reserved.