The chorus asks how long they will have to wait until they can exercise their power of speech in celebration of Orestes. They then call on the Earth that lies over Agamemnon's corpse to help them, for now is the time when Persuasion must come to the aid of Orestes. They also call on Hermes to bring about the deadly confrontation between Orestes and the murderers.

Orestes's nurse Cilissa enters in tears, and the chorus asks her where she is going. The nurse describes how Clytamnestra ordered her to fetch Aigisthos, feigning sadness while laughing inside at the news. For the house, this message spells ruin. Aigisthos will certainly rejoice when he hears of Orestes's death.

The nurse laments the grief she has had to suffer over the years, saying that this new sorrow is by far the worst. She reared Orestes from birth, pacing back and forth throughout the night to quiet his crying. One must tend carefully to a baby, as it has no speech to ask for what it wants. She was a prophet to his desires, but was mistaken many times. Both washerwoman and wet-nurse, she cared for his every need. She was the one who took him from his father's arms, and now he is dead. But now she must bring this news to the man who destroyed the house.

The chorus interrupts the nurse's dirge to ask whether Clytamnestra told Aigisthos to come with his guard. The nurse replies that she told him to come with his guard. The chorus bids her to alter the message, saying that she should bid Aigisthos to come alone, and happily. For, in the mouth of a messenger, a crooked message can be made strait.

The nurse is shocked that the chorus seems to rejoice over the news. The chorus suggests that she should not give up hope for Orestes yet. The nurse remains confused, but the chorus tells her to get on with it.

Once the nurse leaves, the chorus makes a prayer to Zeus, asking him to safeguard Justice. They also call on the spirits of the house to conspire with them, to come and wash the blood from the halls with Justice. With Orestes's act, they trust that Murder will cease to stalk the palace halls. Furthermore, they pray to Apollo, asking him to grant that the house may look up from its veil of gloom and see freedom's bright light.