objectIve. To study the extent of Jehovah's Witnesses' knowledge and acceptance of hemocomponents and hemoderivatives, both fresh and stored, and also to propose a bioethical framework to resolve any ethical and moral conflicts identified in their relationships with physicians and dentists. Methods. A questionnaire was used to interview 150 Jehovah's Witnesses who attend "Kingdom Halls" in the Distrito Federal, Brazil. The questionnaire collected information on socio-demographic data and the use (or not) of hemocomponents and hemoderivatives by those interviewed and also the approach of healthcare professionals to patients of this religion. results. 74% believe that the use of blood causes more harm than benefits to health -refusal is essentially based on the Bible; 96% do not accept hemocomponents, but 76% accept hemoderivatives in specific situations, showing that differing personal interpretations exist; 80% feel would morally offended by the use of stored blood and only 45% by use of fresh blood, confirming the religious interpretation that fresh products are in general more acceptable; according to 83% of the interviewees dentists do not ask about patients' religion, and 71% of physicians do not ask, showing little professional concern with the issue. conclusIon. Jehovah's Witnesses are seen by their "moral strangers" (here physicians and dentists) as the religious group that simply "does not use blood". Although, several blood treatments are nowadays permitted, this does not deprive individuals of the right to refuse blood treatments on free conviction. Personal interpretations frequently increase the list of blood prohibitions and, consequently, the number of moral conflicts, when considering that physicians and dentists usually do not ask about a patient's religion.