No, not as winsome, love-struck Laurey, but as Aunt Eller, the flinty matriarch whose maternal presence hovers over the classic Rodgers and Hammerstein musical.
Duke's show-biz career has spanned more than four decades, but it's those three roles that are etched in the memories of fans of a certain age.
After all, they grew up inspired by the stage and movie versions of "The Miracle Worker." The film won Duke an Academy Award for her portrayal of the blind, deaf and wild little girl tamed by the tenacious Annie Sullivan.
And they were regular viewers of "The Patty Duke Show," the TV series about identical cousins (both played by Duke) - "one pair of matching bookends, different as night and day," according to the show's insistent theme song.
Later, they giggled their way through "Valley of Dolls," a Hollywood trashfest of the highest order that these days, some 35 years after its initial release, has achieved bona fide cult status.
Today, the object of all this adoration sits in a publicist's office directly across the street from the anonymous high-rise that houses the theater where "Oklahoma!" is playing.
At 56, Duke is, well, not 25 anymore, but a stylish matron, smartly done up in a maroon suit, a multicolored scarf draped around her neck, and wearing patent-leather pumps.
Look closely though and the disarming smile is still the same as when she played Patty and Cathy Lane on that ABC sitcom from 1963 to 1966. Duke is eager to embrace "Oklahoma!" - her first Broadway appearance since 1962 when she played a young girl with an incurable heart ailment in a short-lived flop called "Isle of Children."
"I figure at my age, how many more chances was I going to get," Duke says. "So I decided that if I'm going to put my money where my mouth is, then I have to take this risk. Plus, there is some magical, mystical thing about the word 'Oklahoma.' How do you say 'no' to a show like 'Oklahoma!"'
For the last 12 years, Duke has lived in Idaho with her fourth husband, Michael Pearce, and her youngest son, Kevin. Seven of those years have been down a dirt road on a ranch with assorted horses, goats, donkeys, dogs and even a llama or two.
"What I find there has to do with the earth and the animals," she says. "Every time those llamas walk across a pasture, I think I'm in a Christmas pageant. I find a kind of centeredness that is very comfortable." Not bad preparation for playing someone instilled with a pioneer spirit.
"What I feel that I have in common with Aunt Eller is my need and my sense of community," Duke explains. "And my other need is for everybody to make nice. Don't fight. We'll get through this.
"This is a woman who has had strife in life, made her peace with some of it and has come to the point of acceptance. Not giving up."
A mirror of her own life, perhaps? "Yes," she replies simply. That life, its volatile ups and downs, has been well documented not only in several books, including her autobiography, "Call Me Anna," but in a television movie as well.
Her marriages. Her battles with mental illness. Her turbulent relationships with her older children. Idaho is a refuge, she says, from the clutter, noise and anger of big cities but not from herself.
"I don't spend a lot of time analyzing myself anymore," Duke says. "But I have found in the last couple of years, that I don't think that I would have been able to be as settled a 56-year-old person if I had stayed in the city."
What lures her back to show business is an occasional television movie, and something special, such as "Oklahoma!" Despite her long career, the current Broadway revival is only Duke's second musical after a concert version of "Follies" she did last year in California.
Yet she jumped right in.
"I wasn't surprised by her musical ability or her ability to be in a musical," says Mitchell Lemsky, production supervisor for "Oklahoma!" It was Lemsky who rehearsed the actress for nearly four weeks before she went into the show in mid-December, replacing Andrea Martin.
"When I was a kid, I thought I could sing - then I thought I should never try that again," Duke says with a laugh. "But in recent years, I've been singing more around home and the horses don't care and the llamas don't care."
So she started singing lessons with a voice teacher in Spokane and then dancing lessons.
"I do think of myself now as an actor who can sing and who can dance - given the proper support and instruction," Duke says. "And I'm certainly getting that here. Everyone has been so kind. I find that if I dance with the love that I feel for the audience, I really can do it."
"I was surprised by how accessible and open she is," Lemsky says. "She lets herself be known thoroughly, and her generosity in that way was overwhelming. It's genuine, and she brings that quality to her playing of the part. She just doesn't hold back."
Hold back? Not on your life.
To this day, Duke finds it astonishing that total strangers come up to her in airports and sing the theme song to "The Patty Duke Show." And she welcomes them.
"We grew up together. There weren't many other teenagers until Sally Field did `The Flying Nun.' We had a commonality," she says.
"On a personal level, I love it. When you are going through life trying to figure out why you were born ... and then ... people, total strangers, say, `I love you' - I don't know if it gives me the full answer but it carries me on the quest.
"I think I was given a certain set of values by my parents that have stuck with me," she says, "and from `The Miracle Worker' - listening almost every night for almost two years to Annie Bancroft playing Annie Sullivan and saying, `Giving up? Why in my opinion, that's the original sin."'
By Michael Kuchwara