The level of effectiveness of patent enforcement in a country's patent system is a key area of focus in recent international trade negotiations, such as the Trans-Pacific Partnership Agreement. Since the implementation of the Trade-Related Aspects of Intellectual Property Rights (TRIPS) agreement by most developed and developing countries, the focus of such international negotiations has now shifted from expanding provisions related to patent law protection towards provisions that can enhance the effectiveness of patent enforcement in negotiating countries. While these policy-making efforts are driven by an inherent assumption that stronger levels of patent enforcement will positively affect international trade and boost economic growth for countries adopting such reforms, there is currently no empirical evidence to support or oppose this assumption. This paper studies the effect of the strength of patent enforcement on the economic growth of 42 developed and developing countries in the post-TRIPS years 1998-2011, as well as the role of inward foreign direct investment (FDI) in mediating and enhancing this relationship. The results of this study provide support to the policymaking expectations adopted in the negotiations of free trade agreements, in that stronger levels of patent enforcement are found to have a significantly positive effect on the economic growth of both developed and developing countries. Importantly, inward FDI flows have a mediating role in positively boosting this effect for all countries in our sample, and particularly for developed countries.