Depression is a mental disorder with a state of mental depression as the main symptom and is now one of the most common psychiatric disorders of all; it is assumed that around 20% of all people in Western civilisation will experience depression requiring treatment at some point in their lives. As somatic factors often play an important role in the course of the illness and in the treatment of depression, this clinical picture is also treated in psychosomatic clinics. Systemic and cognitive-behavioural therapeutic approaches are used and a wide range of treatment options are offered. Depression can generally be treated well with medication, accompanying psychotherapy and complementary therapies.