BACKGROUND: The study aimed to investigate how psychiatrists handle the diagnosis and treatment of depression in the adult. PARTICIPANTS: Psychiatrists ( METHODS: A clinical vignette presenting a young man with depressive symptoms of moderate intensity having experienced multiples losses during the development and recent past was presented to the participants. Participants were invited to read the vignette and react ("thinking aloud"), followed by an invitation to elaborate on the diagnosis and treatment. RESULTS: A heterogeneous approach towards the diagnosis and treatment of depression was observed. Without a consensus regarding the diagnosis of depressions, two distinct ways to understand the clinical vignette emerged: one pathogenic, identifying the underlying causes of the depressive symptoms, and the other nosological, based on diagnostic criteria. Consequently, proposition for treatment also diverged ranging from psychotherapy, psychotropic medication, complementary and alternative treatments, and paramedical approaches such as ergo- and socio-therapy, at times leaving the choice up to the patient. Possible explanations for this diversity are a more or less strict adherence to diagnostic criteria used by the psychiatrists, be they ICD or DSM, the double training as psychiatrist and psychotherapist which is mandatory in Switzerland, a certain prudence regarding psychiatric diagnoses by fear of stigmatisation, attention to the therapeutic alliance or divergent views on the theoretical and conceptual understanding of depression. CONCLUSION: The results of this study underline the importance to include the epistemology of psychiatric disorders in training to raise awareness and conscientization regarding the influence of epistemological aspects on attitudes and approaches to the diagnosis and treatment of depression and other psychiatric disorders.