"Medeia" was premiered during the 1st Bienal de Ópera Atual, a festival of new chamber operas created for the promotion, diffusion and popularization of new operas in Brazil. Inspired by the Greek tragedy of Euripides (431 BC), the opera's plot begins in Corinth, shortly after Jason left Medea to marry Creusa, King Creon's daughter. Once a mystic and powerful figure, now a woman betrayed and humiliated, Medea decides to take revenge on her husband, firstly killing princess and king, and finally killing her own children, thus exterminating Jason's future in his offspring. Medea presents one of the most impressive female characters in universal drama, for such a profuse range of human feelings that she carries. For the musical treaty of dramaturgy, the protagonist is built in a tripartite form by soprano, mezzo and alto ("Medea is all the women"), in contrast with Jason (tenor) and Aegeus (bass-baritone), masculine figures also antagonistic to each other. This "game of forces" is also underlined by the disparities in range and timbre, in the musical dialogues between: soprano/choir (formed by two of the three female singers, taking turns with the Medea of the moment); mezzo/bass-baritone; and alto/tenor. The libretto structure is: Prologue + 7 scenes + Epilogue, anticipating a musical score also symmetrical, constituted of partial and increasing climaxes for each scene. The English version of the score included here may be an alternative for a new production with a new cast.