Deep brain stimulation (DBS) is a clinically established procedure for the treatment of severe motor symptoms in patients suffering from end-stage Parkinson's disease, dystonia and spontaneous tremor. It is currently being tested for further indications, including psychiatric disorders such as major depression and many other illnesses. However, the ethical issues surrounding DBS require ongoing discussion. Analysing the neuroethical and clinical literature, five main themes have been identified regarding the ethics of DBS in clinical practice: careful examination and consideration of risks and benefits; patient selection; protection of children's health in paediatric DBS; specific issues regarding patient autonomy; and the normative impact of quality of life measurements. When investigating DBS for further applications, issues of research ethics must additionally be considered. In this context, questions such as the additional value generated by the study, how to make scientific validity a reality, which patients should be included and how to achieve an acceptable benefit\/risk ratio are of particular importance. The benefit to patients is central to the ethical evaluation. This criterion can outweigh very serious side effects and can make DBS appropriate even in paediatrics. As standard test procedures elude the central aspects of patient benefit, the measurement of quality of life should be complemented by open, in-depth interviews to get a more adequate picture of the postoperative situation of patients. Further research on DBS is needed to explore its full therapeutic potential. Research should be based on sound scientific hypotheses and proceed cautiously to benefit severely suffering patients without exposing them to undue risk.<\/p>\n\n\n\n