Parliamentary scrutiny reserves have become a popular parliamentary instrument for the scrutiny of EU documents over the last two decades. While the exact provisions for them vary between the member states and according to their parliaments’ overall scrutiny system, parliamentary reserves generally mean that government representatives do not, or cannot, officially agree to a proposal in the Council (or COREPER or the working groups) while the parliamentary scrutiny process is ongoing. Yet despite the proliferation of reserve provisions, we actually know very little about them. The paper will therefore provide an overview over the specific features of scrutiny reserves in different member states. In addition, it investigates whether scrutiny reserves actually are an effective instrument to safeguard parliamentary influence in EU affairs by looking at how they are being dealt with at different levels of the Council negotiations.