The regulation of tax incentives internationally raises sensitive and complex issues, and the WTO plays a fundamental role in establishing a regulatory framework and ruling on disputes involving tax subsidies. In this regard, the "foreign sales corporation" (FSC) cases, which are the first cases referred to the WTO judicative bodies involving the question whether the direct tax provisions at issue are in compliance with the WTO rules, can be regarded as the essence of the legal reasoning of the WTO bodies regarding tax incentives. These cases have gone on for more than three decades. It was only in March 2006 that the final report was adopted. Since matters involving tax incentives are a key element in regulating trade competition in the world, it is essential to set out the WTO jurisprudential standards which have been developed. This article considers the WTO regulatory framework regarding direct taxation and reviews the FSC cases in order to best understand some legal lessons that can be learned from them.