OBJECTIVES: Opioid use disorder (OUD) is a chronic illness, and the ultimate treatment goal is recovery. However, evaluating the effectiveness of OUD treatment based on recovery outcomes is a challenge, as clinical trials typically do not follow up patients long enough to capture important recovery outcomes. This research aimed to synthesise published evidence on the relationship between outcomes measured in OUD clinical trials and long-term recovery outcomes. METHODS:  A systematic review of studies that investigated the relationship between short-term and long-term outcomes of OUD patients was conducted. The search was unrestricted by country or year (up to September 2015), and was performed using the PubMed database and specific conference proceedings. The short-term outcomes included in the search were retention, level of illicit opioid use (on-top use), abstinence, cravings, and withdrawal. The long-term outcomes of interest included relapse, mortality, comorbidity, quality of life, crime, diversion, misuse, absenteeism, employment, social integration, caregiver impact, and impact on family. RESULTS:  Out of 1,220 relevant records, 89 studies met our criteria for data extraction. Three of the short term outcomes were well covered by the literature: medication retention, on-top use, and abstinence. The long-term outcomes most frequently reported were retention, relapse, mortality, comorbidity, and crime. Specifically, retention was found to be associated with lower rates of relapse, death, criminal activities, HIV infection, severe depression, and unemployment; accordingly, retention was also associated with better quality of life and interpersonal relationships. On-top use was linked to lower long-term retention and increased crime rates. Little evidence was found to link cravings and withdrawal symptoms to long-term outcomes. CONCLUSIONS: This review identified published studies that confirmed improved medication retention as a predictor of a variety of recovery outcomes. Further studies are warranted to validate such a link and to quantify the effect of OUD treatments on recovery.