On 27 May 2015, a Green Warbler Phylloscopus nitidus was caught and ringed at Blåvand Bird Observatory, the westernmost point in Denmark. The species is challenging to identify on morphological basis alone, and the bird’s identity was confirmed with phylogenetic analyses of mitochondrial DNA sequences. This constitutes the first record of Green Warbler in Denmark, the third record in Fennoscandia – following records on Öland, Sweden, on 29 May 2003, and Åland, Finland, on 20 May 2012 – and the eighth vagrant record in Europe outside the species’ very restricted peripheral breeding range. © 2017, University of Lund. All rights reserved.