Substance use disorder (OUD) is a treatable, chronic disease that often involves cycles of relapse and remission. Individuals who are under the influence of these substances often engage in risky and compulsive behaviors that result in harm to themselves or others. Medication-assisted treatment (MAT) has been proven to successfully treat OUD through various mechanisms including, reducing or eliminating withdrawal symptoms, blunting or blocking the euphoric effects of illicit opioids, relieving cravings, and normalizing brain chemistry and body functions without having the negative effects of the illicit substance. Despite its effectiveness, MAT is not widely used by providers to treat patients with OUD. A major reason for this is that many health professionals are not properly trained in using MAT. There is also a misconception that using MAT is simply substituting one drug for another. This activity describes the mechanisms and effects of different drugs used to treat opioid use disorder and the prescribing of these medications.