- This act takes place in the old garden of the Prozorov house. The household and friends are saying good-bye to the departing soldiers. Fedotik and Rohde pay their respects and leave.
- Kulygin has shaved his mustache and apparently looks really bad without it.
- Irina is worried because of some friction between Tuzenbach and Solyony. More updates: she has finally consented to marry Tuzenbach, plus she's gotten her teaching certificate.
- Olga has become headmistress and moved in at the school, so Irina has been alone in the house with Natasha. Sounds like torture. Not to mention that Protopopov has become a regular fixture.
- Masha is waiting for Vershinin to arrive. She's anxious and unhappy.
- Pushing the baby carriage around, Andrey comes over to Chebutykin and Masha. Chebutykin fills him in: Solyony has challenged Tuzenbach to a duel.
- Duels used to be a big deal in Russia.
- Andrey is worried about being in the house alone. He doesn't really consider his wife a human being anymore.
- Chebutykin advises him to walk off into the sunset. Hey, when did we move from Russia to the Old West?
- Solyony enters; he and Chebutykin leave for the duel.
- Ferapont enters with papers for Andrey.
- Tuzenbach enters and talks with Irina. She's still honest about not loving him. He says goodbye to her and she has a premonition that he won't be coming back. She doesn't try to stop him, though.
- Andrey confesses to the deaf Ferapont all his regrets and disappointments. He must really like not being listened to.
- Natasha yells shrewishly from the window for Andrey to be quiet. Speaking of not being listened to...
- Anfisa is delighted that she gets to live with Olga at the school.
- Vershinin appears. He asks Olga to help with his wife and girls (remember, he's heading off with the army). Then has a tearful farewell with Masha.
- Masha is sobbing and Kulygin enters. In typical appearances-before-emotions form, he promises not to reproach her.
- Natasha emerges and declares her intention to cut down all the trees in the garden. She criticizes Irina's belt (remember how we first met her?).
- A march is played; the soldiers are leaving.
- Chebutykin comes in with bad news: the baron has been killed.
- The three sisters stand close to each other, feeling pretty surly about their lives, their suffering, and the need to start over. Yep, that's basically how the play began, too.
- Everyone heaves a sigh.