AbstractThe Doctor of Myddfai(1995), Peter Maxwell Davies's third full-scale opera and his first collaboration with David Pountney, is a work that occupies an important position within the composer's output for the opera house and theatre. However, whereas a significant amount of scholarly attention has been afforded to Davies's music-theatre works of the 1960s and the operasTaverner(1962–8) andResurrection(1986–7),The Doctor of Myddfaihas been somewhat neglected by comparison. This article examines the opera from two perspectives. The first addresses the work's dystopian setting and argues that key issues highlighted in the libretto – especially in relation to certain political concerns and environmental anxieties – have a strong contemporary resonance. The second focuses on the opera's articulation of Welsh identity, particularly through the use of Welsh folklore, native landscape and place, and indigenous musical signifiers. The intersection of these two elements – the work's celebration of Welshness and its dystopian qualities – imbues the opera with an intrinsic yet highly productive sense of tension and opposition: characteristics that drive the work towards its compelling conclusion.