Although the European Union pledges to ‘maintain [and reaffirm] the credible enlargement perspective for the Western Balkans,’ (European Commission, 2018), some of the new requirements which it demands the Western Balkan candidate states to meet in order to gain membership seem to be very demanding for the political leaderships of these states. This is particularly the case for the requirement that candidate states solve all their ‘bilateral disputes…as a matter of urgency’. While Montenegro hopes to solve its only remaining (though nearly thirty year old) dispute with Croatia over their maritime border sometime soon, the second regional frontrunner for EU membership, Serbia, and the other remaining Western Balkan states (with the partial exception of Albania) have many more (and more serious) problems to resolve with their neighbours. This article discusses the nature and origins of problems in several most complex bilateral relationships in the Western Balkans and critically assesses the difficulty these problems pose for the Western Balkan states’ accession to the EU.