When serving abroad, diplomats must abide by both the diplomatic functions detailed in the 1961 Vienna Convention on Diplomatic Relations and the Convention’s general obligations. This applies, too, to the European Union’s missions (Union delegations), which execute diplomatic functions for the eu in third countries. These diplomatic activities are more severely constrained than for individual member states by the limits set by eu law in terms of the horizontal and vertical division of competences. This article demonstrates how Union delegations fulfil nearly all traditional diplomatic tasks outlined in the Vienna Convention, while going beyond the traditional conception of diplomatic functions in terms of human rights protection, the execution of administrative programmes, and the management of coordination/cooperation modes with eu member state missions on the ground. Ultimately, the article argues that Union delegations are able to meet the demands of modern diplomatic interchange and may have inadvertently altered diplomatic functions altogether.