自主原則係指患者在理性狀態下有權決定自己的行為，包括決定及選擇醫療專業人員及治療方式；醫療人員認為對患者有益的醫療行為亦應先得到患者之充分授權或認可。因此自主原則常被認為易與傳統的醫主原則相衝突，整合或協調「病人自主」與「醫主」兩大原則，有賴於良好的醫病溝通；其基本前提在於醫師應能充分提供患者可理解的病情知識與治療方法及可能引起的利與弊，以獲取病人的同意。健康照顧的基礎在於建立及尊重患者之「自主性」，本大主要以此為主軸，並以「知情同意」為範例，討論其內涵及相關之影響因素與衍生之問題。「知情同意」常用的表達方式為同意書簽署，其主要功能在於表現其對患者「自我決定權」的尊重，鼓勵患者能更積極主動地參與治療決定。簽署同意書應視為一動態「過程」，而不是一紙靜態的「證明文件」。簽署的過程包含了資訊的提供、患者之充瞭解、主動意願、同意簽署、醫事人員之教育患者而獲患者之主動同意；整個簽署過程對於治療進行通常具有正面價值。自主原則為人性醫療的根本準則，其徹底落實有賴於倫理教育品質的提昇；以個案為中心、以實例為基礎之啟發性討論式教學，配合臨床實習與督導，及師長的床邊教學與臨場示範等身教方式都是培養醫學生未來能尊重及創造患者「自主」的有效方式。

　　　　　The principle of autonomy indicates that rational individuals should be permitted to be self-determining. Respecting patients' autonomy has been considered as the basis of health care. The emphasis on autonomy in a medical ethical system asserts that the patient has the rights to make personal decisions about the health-related issues including choosing therapists, diagnostic procedures and recommended treatment modalities. However, patient's autonomous actions that harm oneself, or another, or are offensive to law and morality are not to be defended. How to integrate and balance the patient's autonumy and the professional's paternalism in patient care depends on effective patient-physician communication. This review focuses on the issues of informed consent and truth telling, which are major rules derived from the principle of autonomy. These provide a corrective mechanism to paternalism and give the pateents the opportunity and encouragement to be more actively involved in decision making. Informed consent is not only a legal doctrine, but a series of dynamic interactional processes that provids an autonomous patient with the information and understanding needed to choose autonomously to authorize a procedure. Its most important function is expressing respect for the self-determination of patients. The essential components of the consent process, all basic to clinical medicine, should contain: 1) disclosure of adequate information including recommended investigations, benefits, risks, and alternatives; 2) patient's comprehension of the provided information; and 3) voluntaries and active consent. Effective communication skill and supportive techniques on the parts of medical professionals are strongly needed to facilitate patients' understanding and willingness to give consent during the process. In addition, physicians' positive attitudes that are important to enhance the validity of informed consent include the following: emotional security about possible rejection of medical advice, readiness to accept variants of patients' personal values, acknowledging medical uncertainty, and willingness to converse patiently with the patient. It is clear that respect for patients' autonomy is necessary to ensure the quality of health care. The effective implementation of this principle depends on the education of medical students toward not only ethical reasoning, but also medical humanity. A proposed teaching strategy is to use a case-centered, problem-based, small-group tutorial mode in addition to integrated didactic lectures. Furthermore, courses that focus on the formal practice of medical ethics and medical humanity through giveing students the chance to practice and learn under the teacher's guidance in daily clinical settings are exphasized.