Opioid use disorders can be treated with psychosocial interventions which aim to increase quality of life and minimize problems maintaining drug use. In addition, pharmacological treatment with opioid maintenance therapy (OMT) can help minimize morbidity and mortality. The principle for OMT is substituting to another opioid with a more favourable pharmacological profile, primarily buprenorphine or methadone. The first choice is buprenorphine in combination with naloxone. The aim of this review is to summarize current principles for handling patients in OMT.