Resumen: This paper aims to research the refusal of Jehovah’s Witnesses regarding the application of blood transfusion treatments, particularly in minors. Spanish legislation and some solutions of comparative law are analyzed. In short, in the case of minors, progressive autonomy must be addressed in order to establish whether they can make decisions that could harm their health. It is proposed to review the Spanish legislation and doctrine on the matter in order to articulate an adequate solution to the working hypothesis. It is proposed to thoroughly analyze the primary and secondary sources on the refusal to receive a blood transfusion in minors in Spain.