Opioid use disorder (OUD) is a treatable chronic disorder with episodes of remission and recurrence characterized by loss of control of opioid use, compulsive use, and continued use despite harms. If untreated, OUD is associated with significant morbidity and mortality. Buprenorphine and methadone reduce fatal and nonfatal opioid overdose and infectious complications of OUD and are the first-line treatment options. Physicians have an important role to play in diagnosing OUD and its comorbidities, offering evidence-based treatment, and delivering overdose prevention and other harm reduction services to people who continue to use opioids. Interdisciplinary office-based addiction treatment programs support high-quality OUD care.