In an era of increasingly globalized trade, pharmaceutical patents play a key role in the availability and affordability of medicines, as shown by the conflict over access to antiretroviral medicines for people living with HIV/AIDS in resource-limited countries. Patent protection can also be a contentious issue in high-income countries, when high medicine prices impede access to effective treatment. Governments grant intellectual property rights as an incentive to produce inventions that will benefit society as a whole. The varied extent of protection and enforcement of these around the world became a source of tension in international economic relations, leading to international negotiations within the World Trade Organization (WTO). These negotiations resulted in the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS), which is a set of trade rules meant to introduce a global system to monitor and enforce the protection of intellectual property rights among WTO members. TRIPS covers five essential issues— • How to apply basic principles of the trading system and other international intellectual property agreements • How to give adequate protection to intellectual property rights • How to enforce such rights adequately in a country’s own territories • How to settle disputes on intellectual property among members of the WTO • What special transitional arrangements to apply during the period when the new system is being introduced Developing countries expressed concerns regarding the possible effect of TRIPS, including the following— • TRIPS treats medicines like any other commodity, but medicines are not ordinary consumer products. • Prices will likely be higher for new medicines in countries with no previous patent protection. • Generic competition will be delayed in countries with a previous patent term less than twenty years. • The local pharmaceutical industry could be weakened, and dependence on developed countries may increase. • TRIPS may not improve research and development (R&D) decisions regarding treatments for the diseases common in poor countries. The minimum standards required by TRIPS resulted in developing countries losing some capacity to regulate pharmaceutical patents and control the cost of medicines; however, the agreement left some flexibility for them to take measures to protect public health. Because the provisions relating to patents and pharmaceutical regulation are confusing and contentious, regulators must acquire the relevant technical expertise to use these flexibilities within TRIPS to improve access to medicines. The international rules regarding intellectual property are evolving quickly. Developing countries must actively participate in discussions of the future of the intellectual property system to ensure its appropriateness for countries at very different levels of development. As the rules evolve, their impact must be properly understood if policies are to be based on relevant evidence.