The aim of this specialistic study is to show whether quetiapine has a place in the treatment of depression and to present the problem and severity of the depressive disorder as a disease. The work could contribute to the future development of guidelines for the treatment of depression, the inclusion of quetiapine and its role in the therapeutic procedure, as well as monitoring the safety of the drug monotherapy or in combination with other antidepressants. Material and Methods: In the design and shaping of this specialistic study, original and review scientific papers have been searched. The literature has been systematically reviewed in the field of mental disorders and psychopharmacotherapy. Abstracts of drug properties were used, medical literature, PubMed, Web of Science, Cochrane databases were searched for keywords: depression, major depressive disorder, atypical atipsychotics, quetiapine, antidepressants, comparison of the effect of quetiapine with other atypical antipsychotics in major depressive disorder. For the purposes of this specialistic study, a questionnaire was developed and administered to subjects (patients) at the Zagreb City Pharmacy who are taking the drug quetiapine for the treatment of depressive disorder. Conclusion: Although depression is one of the leading health problems today, about half of depressed patients remain unrecognized, most are untreated, and only a small number are treated according to modern principles. For the correct and successful treatment of depression it is important to give a correct diagnosis of depressive disorder in relation to the intensity and accompanying comorbidity. Until today, various therapeutic options are available on the market in the treatment of depressive disorders such as antidepressants with different mechanisms of action, augmentation therapies like antipsychotics, mood stabilizers, and some hormones, and finally electroconvulsive therapy and psychotherapy like non-pharmacological methods. A particularly big problem in the treatment of depressive disorders is the major depressive disorder. Often, major depressive disorder is accompanied by psychotic features and anxiety or personality disorder as accompanying psychiatric comorbidity, which significantly impedes the day-to-day psychosocial functioning of the patient, and antidepressant therapy alone is no longer sufficient for successful treatment. All of this ultimately results in less patient adherence. When reviewing the literature and conducting the survey, atypical antipsychotics, especially quetiapine, proved to be a very successful augmentation therapy. Administration of this drug leads to a reduction in anxiety and psychotic symptoms and to the regulation of sleep, which patients have most often complained about. Furthermore, it has been shown to be effective in reducing the onset of residual symptoms and increasing the rate of remission. The incidence of adverse reactions has also been shown to be quite low, especially when it comes to acute extrapyramidal symptoms, which are often an accompanying side effect of antipsychotics, especially the first generation. Due to all this, augmentation of quetiapine antidepressant in clinical practice has proven to be an effective and safe option in the treatment of major depressive disorder, which leads in the long term to the functional recovery of patients.