This working paper reviews the findings of the most prominent studies on the economic impact of the Transatlantic Trade and Investment Partnership (TTIP), focussing on those commissioned by the European Commission and by the German government. It casts doubt on the methods used and concludes that the gains are likely to be minimal. It also shows that the analyses are one-sided, considering the costs of regulations but not the benefits. It shows that negotiations could result in a harmful diminution of regulations in a number of areas. It concludes that even a small reduction in the benefits of regulations due to the TTIP could dwarf the very small economic gains put forward by the impact studies.