There is evidence that the endogenous opioid system in the brain plays an important role in mood regulation, and disturbances in its functioning may lead to the occurrence of depressive disorders. One of the drugs that affect the endogenous opioid system in the CNS is buprenorphine. The article is areview of the studies on the effectiveness of buprenorphine used as an augmentation of antidepressant treatment. The selection of articles was made by browsing the Medline and PubMed databases with the use of key words ‘buprenorphine’and ‘treatment of drug-resistant depression’. The analysis included thirty one studies. The results indicate that buprenorphine may be effective in drug-resistant depression in a similar manner as other augmentation strategies added to antidepressant treatment. Co-administration of buprenorphine and samidorphan may reduce the risk of addiction without losing the antidepressant effectiveness of buprenorphine. Further methodologically correct studies in this field are needed. In addition to being a partial agonist of the µ receptor, buprenorphine is also a potent antagonist of the kappa type opioid receptors. The antagonism of µ receptors alone does not cause antidepressant effects. Antagonism towards kappa receptors may cause antidepressant effects as well as reduce the severity of anhedonia. Depressed patients who do not respond to standard antidepressant treatment may have dysfunctions of the kappa receptor that are similar to opioid addicts.