<p dir="ltr">Opioid-related harms have been increasing in Australia over the last 5 years. Patients with opioid use disorder are over-represented in ED presentations. Opioid agonist treatment is the most effective community-based treatment. Buprenorphine is considered the safest of these treatments to use in the ED setting. This rapid review investigated the effectiveness of initiating buprenorphine in the ED setting. </p><p dir="ltr">Medline, Embase, Emcare, PSYCinfo, CINAHL and Cochrane Central Register of Controlled Trials databases were searched. Randomised and non-randomised studies published in peer-reviewed journals that involved the initiation of buprenorphine in the ED setting were considered eligible. </p><p dir="ltr">The search revealed 350 articles of which 11 were included in the review; three articles representing two randomised controlled trials (RCTs) and eight observational studies. Data were extracted from included papers and risk of bias assessed on the RCTs. One well-conducted RCT showed that buprenorphine initiated in the ED does improve treatment engagement up to 2 months after an ED visit. Eight observational studies, one with a comparator group reported positive results for this intervention. </p><p dir="ltr">There is strong evidence that clinicians should consider commencing buprenorphine in the ED for patients with opioid use disorder when combined with a direct and supported referral or ‘warm handover’ to community care. Further implementation studies and investigation of long-acting injectable buprenorphine treatment are required.</p>