The development of a postmodern society, oriented on the implementation of various kinds of reforms, gives rise to the newer branches of law. The medical law, which serves for a defining sphere of public administration in the field of health care, is not an exception since the life and health of citizens are an integral part of Ukraine's national security. That is why it becomes relevant to provide administrative and legal characteristics of the genesis of medical law into the legal system of Ukraine. The aim of the study is to substantiate the necessity to introduce a medical law institute into the legal system of Ukraine. The empirical basis of the study relies on a survey of 350 health care professionals to determine the relevance of establishing a medical law institute and its structural elements. It was established that the sub-institute (sub-branch) of medical law is a structural element of the law system, which is a separate part of the relevant sphere (branch) of law, regulating the respective groups of public relations in the field of health care. It was proved that the subinstitute (sub-branch) of medical law is a set of homogeneous social relations that regulate health care activities and comprehend providing a full range of quality medical services on the basis of the current legislation.