This article analyses “The Breasts of Tiresias” (1903), especially considering the preface and the prologue of the play, both written in 1916, in which Apollinaire reiterates the criticism that was made to the theatrical model at that time and defends theatrical presuppositions fundamental to dramaturgy that developed throughout the twentieth century.O presente texto trata de As mamas de Tirésias (1903), considerando especialmente o prefácio e o prólogo da peça, ambos escritos em 1916, nos quais Apollinaire reitera a crítica que se fazia ao modelo teatral vigente e defende pressupostos teatrais de fundamental importância para a dramaturgia que se desenvolveu no decorrer do século XX.