The TTIP will – like other free trade agreements (FTAs) – violate one of the cornerstones of the WTO, i.e. the Most-Favoured-Nation (MFN) principle. However, the multilateral trading system has since 1947 permitted the formation of trading blocks and preferential bilateral trading partnerships. This contribution asks how the WTO can fulfill its task of ensuring that FTAs do not systematically undermine the multilateral trading order. It focuses on the issue of transparency in the current oversight process and discusses whether the WTO secretariat should be granted a stronger mandate to proactively investigate the economic effects of the notified FTAs.