OBJECTIVES: Treatment discontinuation in psychiatric care is a major cause for the deterioration of mental health problems. This study assessed reasons for treatment discontinuation of patients suffering from schizophrenia or depression in a local mental health care system in Germany. METHODS: A retrospective survey was performed to assess how coordination of care through mental health care providers in the Rhein-Kreis-Neuss region (Germany) is organized. Within this survey reasons for treatment discontinuation were explored from the perspective of providers and patients. 88 providers of care (60 institutions) and 30 patients diagnosed with schizophrenia and 17 patients diagnosed with major depression were interviewed using in-depth face-to-face interviews. Additionally providers were qualitatively interviewed on strategies to prevent discontinuations. RESULTS: Providers were asked to rank pre-specified reasons for treatment discontinuation according to their occurrence (often, occasionally, seldom, never). 38.8 % ranked non-adherence to medication as often, 38.1 % waiting times for next treatment. 25.6 % identified problems in the patient’s social environment as being often a reason for treatment discontinuation, 23.7 % mentioned revolving doors effects, 19.3 % resistance to therapy and 12.3 % lack of communication between providers. Patients diagnosed with schizophrenia (mean age 45 years; mean duration of illness 16 years) and depression (mean age 45 years; mean duration of illness 13 years) indicated that they consider discontinuation or actually discontinue treatment when there is a lack of social integration or when there is no reaction of providers to articulated problems with treatments. In response to an open question on suggestions for improvement, providers recommended better cross-sectoral coordination, earlier start of treatment and early return to normal daily living as appropriate measures. CONCLUSIONS: From the subjective perspective of providers and patients a variety of causes seem to influence treatment discontinuation. More research into specific interventions to improve treatment adherence is needed.