[The regulation of supplementary health care in Brazil from 2000 to 2018].

This article analyzes the performance of the Brazilian National Regulatory for Private Health Insurance and Plans Agency (ANS, acronym in Portuguese) in the regulation of care in the sector from 2000 to 2018. After documentary analysis, the main initiatives of the regulatory dimension were characterized in the five terms of the agency's board of directors in the period. Furthermore, the study explores the legal and infra-legal norms related to the theme and the ANS main actions to guarantee coverage and qualification of the assistance offered by operators and service providers. These regulations were organized into three axes of care regulation: list of procedures and events in healthcare and care coverage; care segmentation; and Initiatives for health promotion, disease prevention, and qualification of care. We observed that the measures of care regulation implemented followed a continuity trend, despite the variation in political orientations and professional trajectories of their CEOs or the configuration of the collegiate board. This can be attributed to factors such as the professionalization of the regulation and the establishment of ANS institutional framework. Despite the micro-regulatory nature of the agency's performance, care regulation contributed to the promotion of comprehensive care for health plan beneficiaries and to the induction of better care practices by operators and their service providers. However, companies stakeholders still pressure public managers, aiming at making care regulation more flexible.