Admission of a patient in the Intensive Care Unit (ICU) is justified when the critical situation can be reverted or relieved. In spite of this, there is high mortality in the ICU in regard to other hospital departments. End-of-life treatment of critical patients and attention to the needs of their relatives is far from being adequate for several reasons: society denies or hides the death, it is very difficult to predict it accurately, treatment is frequently fragmented between different specialists and there is insufficient palliative medicine training, including communication skills. There are frequent conflicts related to the decisions made regarding the critical patients who are in the end of their life, above all, with the limitation of life-sustaining treatments. Most are conflicts of values between the different parties involved: the patient, his relatives and/or representatives, health professionals, and the institution. The SEMICYUC Working Group of Bioethics elaborates these Recommendations of treatment at the end of the life of the critical patient in order to contribute to the improvement of our daily practice in such a difficult field. After analyzing the role of the agents involved in decision making (patient, familiar, professional, and health care institutions), of the ethical and legal foundations of withholding and withdrawal of treatments, guidelines regarding sedation in the end of the life and withdrawal of mechanical ventilation are recommended. The role of advance directives in intensive medicine is clarified and a written form that reflects the decisions made is proposed.