The transfusions of blood and blood products have the essential meaning in contemporary medical therapy. They are also potential source of confl icts between patient’s and doctor’s conscience. The religious beliefs forbidding blood transfusion have accounted for the main ethical, religious, legal and transplantology problems in the last decades. Jehovah’s Witnesses are the most numerous and the widest religious group which refuses blood products transfusions. They have acted as religious association since 1905 (legally from 1989) in Poland. The number of Jehovah’s Witnesses in Poland is between 120.000 and 130.000. The Jehovah’s Witnesses, referring to religious orders, refuse transfusions of the blood, plasma, packed red blood cells, leucocytes and thrombocytes, even in the face of ife-threatening situations. These situations are diffi cult both for a doctor and a patient and they can be the source of doctors’ dilemmas in relation to patients’ autonomy, informed consent and professional secrecy. It is worth saying that that though nowadays contemporary medicine can use effective alternative methods in relation to blood products transfusion, those methods are not commonly accessible. In this work the authors refer some Jehovah’s Witnesses’ opinions in relation to blood transfusion and ethics, deontological and legal aspects with regard to blood products transfusion for the Jehovah’s Witnesses. Key words: Jehovah’s Witnesses, blood transfusions, medical ethics.