This article discusses the evolution of the international intellectual property rights system in three phases and the implications for public health, especially for the implementation of policies for access to medicines. During the first phase, characterized by the Paris and Berne Convention, signatory countries defined which technological fields should be protected (or not). Under the second phase, with the enforcement of the WTO TRIPS Agreement, countries are obliged to grant patent protection for all technological fields, including for the pharmaceutical industry. Within their national legislations, countries also have the opportunity to implement access to TRIPS flexibilities for medicines. With the third phase, characterized by the negotiation and signing of bilateral and regional free trade agreements, countries will have to implement TRIPS-plus provisions which may have negative implications for the TRIPS flexibilities as well as for policies for access to medicines. The authors conclude that the currently proposed international intellectual property rights system favors patent-holder rights and that a balance is needed between patent holders' and health rights.