This article analyzes the spread of intellectual property in trade agreements. We explain how the integration of intellectual property with international trade rules led to the globalization of pharmaceutical patenting, and then how additional provisions related to pharmaceutical products have been introduced by regional and bilateral trade agreements. We describe the additional ‘TRIPS-Plus’ rules contained in recent trade agreements, which go beyond the requirements of the World Trade Organization’s TRIPS Agreement, and explain the potential challenges that they may create for developing countries. We draw attention to the conceptual and methodological challenges of assessing the effects of patent provisions in trade agreements on prices and access to drugs, with particular emphasis on the importance of timing. Depending on when countries began allowing drugs to be patented, TRIPS-Plus provisions have different effects; and when pharmaceutical patenting has been in place for more countries for more time, the effects of TRIPS-Plus provisions will change again