Act I

Set around 1907, in what is now the state of Oklahoma, a group of local farmers, cowmen and their families greet the new day (Oh What a Beautiful Morning). Curly, a young cowboy, comes to Aunt Eller's farm intending to ask her niece, Laurey, to go with him to the 'box social' that night (The Surrey with the Fringe on Top). Laurey is tempted to go but, suspecting that he has made the whole thing up, she spurns his invitation.

In the meantime another cowboy, Will Parker, has just returned from Kansas City (Kansas City), filled with stories of the big city. Will is engaged to Ado Annie Carnes, but her father won't let them marry until Will has $50. While Will was away, Ado Annie had become involved with Ali Hakim, a roving peddler, because, as she tells Laurey, she can't say no (I Cain't Say No!) When Annie's father finds out about it, he 'persuades' the peddler, with the aid of a shotgun, to marry his daughter. Ali feels trapped (It's a Scandal).

Laurey has angered Curly by accepting the invitation of Jud Fry, the sinister hired hand, to take her to the 'box social.' The women and girls stop by on the way to the party and one of them, Gertie Cummings, starts to flirt with Curly. Laurey tries to show how little she cares (Many a New Day). Later on, when they meet again Laurey confronts Gertie. Laurey and Curly express their love to each other (People Will Say We're in Love).

Curly decides to go to the smokehouse to convince Jud to give up Laurey. The tormented Jud does not welcome Curly and becomes even more upset by Curly's suggestion that if he hanged himself, it would be the firt popular thing he ever did (Pore Jud is Daid). Their quarrel is interrupted by Ali Hakim and Curly leaves. Ali tries to peddle 'arty' postcards but Jud is not interested. He is looking for a means to get rid of Curly. Left alone he sings (Lonely Room).

Hoping to foresee her future Laurey takes a sniff of the 'Elixir of Egypt,' which she had earlier bought from Ali Hakim. She realises how much she loves Curly (and how dark her future with Jud could be (Laurey's Dream) She is awakened to to reality by Jud who has come to escort her to the box social.

Act II

At the box social, Judge Carnes tries to bridge the antipathy between the two warring groups (The Farmer and the Cowman). Ali Hakim manages to arrange $50 for Will so he can get Ado Annie back. The auction for the girls' hampers of home-cooked food begins. Ali 'wins' Ado Annie's hamper and Will gets Ado Annie. A dual of bids ensues between Jud and Curly for Laurey's hamper. Curly sells everything he possesses and manages to outbid Jud. Jud tries to take his revenge but fails.

Ado Annie and Will finally set their wedding date, but under certain rules (All Er Nuthin'). Jud violently tries to get Laurey back to him, but she fights back and fires him. When Curly finds her all shaken up, he asks her to marry him.

Three weeks later Laurey and Curly are celebrating their marriage. Their friends sing the praises of Oklahoma (Oklahoma!). Jud arrives drunk and during the fight that breaks out between him and Curly, Jud falls on his own knife and is killed. Although Sheriff Cord Elam wants to jail Curly, Judge Carnes is persuaded to hold court there and then and pronounces Curly not guilty. A celebration of a promising new life breaks out and the young couple leave for their honeymoon in a surrey with a fring