A state's denunciation of a treaty with the sole objective of re-acceding to it with a reservation may be interpreted as circumventing the prohibition of the late formulation of reservations enshrined in Article 19 of the 1969 Vienna Convention on the Law of Treaties. This article addresses five cases where the denunciation of and re-accession to a treaty was at least considered by certain states and whose analysis promises to clarify the legal characteristics of this practice. One instance involved such a practice being discussed by the Swiss Federal Tribunal in the context of the amendment of the Swiss interpretative declaration to Article 6(1) of the European Convention on Human Rights. Another instance involved Trinidad and Tobago and Guyana with regard to the Optional Protocol to the International Covenant on Civil and Political Rights. A further situation arose when in 2002 Sweden denounced and re-acceded to the Council of Europe Convention on the Reduction of Multiple Nationality and on Military Obligations in Cases of Multiple Nationality with the aim of excluding the obligations contained in Chapter I of this treaty. The last case analyzed in this article is Bolivia's denunciation of and re-accession to the 1961 Single Convention on Narcotic Drugs. The aim of this article is to offer a critical appraisal of this practice under international law. The article argues that the European states' position differs from the generality of states. In addition, states may include specific provisions on the possibility of denouncing and re-acceding with a reservation when they draft their treaties. States may review more systematically the treaty action and object to practices that are not compatible with the reserving states' good faith treaty obligations. And the ILC may include this topic into its work programme, for example, when updating the Guide to Practice on Reservations to Treaties.