Thirty percent of cancer patients experience depression during the course of their illness. Depression may occur at several key-moments: after diagnosis, a relapse, in the context of treatment failure. Depression is correlated with biological factors due to illness itself and its treatments, but also with inappropriate coping strategies. Diagnosis of depression is not straightforward in cancer patients. Its phenomenology is specific. Moreover, patients as well as clinicians may be reluctant to address the problem of psychological well-being. The treatment of depression has proven to increase quality of life as well as satisfaction with treatments and compliance. Antidepressants are the first line treatment. Psychotherapy and several psychological interventions are considered to be a valid alternative. In most severe cases a combined treatment is mandatory. [References: 6]