In 2002, Belgium adopted a law decriminalizing euthanasia in certain situations. One of this law’s particularities is that it opens the physician’s possibility to practice euthanasia following a patient’s request, which can be based on a constant and unbearable psychic suffering, in the context of a serious accidental or pathological affection, even without a fatal outcome in the short-term. However, this law raises serious ethical issues in the field of mental health, both concerning the concept of diagnosis in psychiatry as well as the incurability of mental illness. This may result in dangerous interpretations. The psychiatric function itself appears to be rather destabilized and challenged by the application of this law. Excesses are possible, and an in-depth reflection is thus paramount concerning the need to better protect the rights of the most vulnerable, such as, among others, the mentally ill.