This thesis seeks to provide a brief account of several problems associated with medical negligence in medical malpractice actions to recover damages and suggest some new ideas from the critical point of view. The summary of the thesis is as follows. First, more refined definition and analysis is due on medical negligence as one of medical treatmentrelated terms. So far, it is not yet well distinguished in its concept and coverage from treatment negligence and medical malpractice. Second, medical negligence is part of civil negligence approached from the medical perspective. Thus, the legal application of the notion of negligence should be studied with the secret, discretionary, and a prompt judgmental nature of medical acts in mind. Third, medical negligence poses a central issue in the medical malpractice actions to recover damages, regardless of whether claims arise under tort or in contract law. Although civil medical negligence to be established in the medical malpractice actions for damages is a so-called "abstract negligence," the duty of care owed by average or customary practitioners is that of the highest attention duty of care. Nonetheless, the term "highest attention duty" has been understood as an abstract standard, which is a mere combination of several elements at the most. It is hoped that more studies should be devoted to the refinement of its meaning. Fourth, the precedents of the Supreme Court of Korea attributes the highest attention duty of care to medical practitioners, and negligence is practically presumed in the proof of medical negligence. However, such an approach has been a matter of dispute because it is ambiguous which duty of care is violated, and medical negligence is merely inferred from the totality of circumstantial facts such as a close proximity in time in the occurrence of events or the absence of intervening causes, etc. A refinement and further development is in demand. A continued use of some legal expressions, which have been established by the Supreme Court precedents since the 1990s, constitutes another problematic area. Some scholars, who are probably confused because of ambiguous expressions in the precedents, argued that the presumption of negligence is based on the so-called theory of probability. As an example, one of the hardened expressions "the burden of proof is alleviated … under the presumption of causal relation between medical negligence and damage" should be modified to the more accurate statement that "the burden of proof is alleviated … under the presumption of both medical negligence and the causal relation between medical negligence and damage." The Court in its precedents has maintained its position requiring that negligence be established in the areas of both common knowledge and specialized medical knowledge. Such problematic position should be settled to the direction in which medical negligence is established by practically presuming negligence in the specialized medical knowledge. The highest attention duty of care is required to a medical practitioner, i.e., an average or customary practitioner. The highest attention duty, although it has only an abstract meaning, remains as a constant in its relation to medical negligence; whereas the level of best medical knowledge and clinical medical practice constitutes variables measured in the framework of relevant time period and local environment. Negligence shall be established by considering the functional relation between the above constant and variables, uninterruptedly examining whether the balance between them has remained intact, and searching for a new factor triggering a shift in the balancing point. As an example of one novel variable, we might want to consider adding a normative standard level to the standard of care, as it had been already adopted in Japan, not limiting relevant factors to merely social and environmental elements in clinical medical practice. It is high time for us to examine the above approach. The Republic of Korea has experienced dynamic advances during the past 50 years since 1960 in legal as well as all other aspects. During those time periods, up until the 1990s, it is fair to say that medical practitioners remained unilaterally favoured; thereafter, the protective shield had been drastically shifted in favor of patients up until 2000. Currently, we find the point is again on the move, which is sudden but desirable, to establish a new balancing point without tipping over to either direction. We must remain alert to the movement of a shifting point and discuss whether the balancing test rules are suitable for a dispute resolution in the mediation of conflicting interests.