Somewhere en route from dirt-poor Mississippi schoolgirl to TV news anchor to talk-show empress to award-winning actress to therapist for an anxious nation, Oprah Winfrey became a businesswoman. It's a title she doesn't like much. "I don't think of myself as a businesswoman," she announces at the beginning of a four-hour sit-down--the first extensive interview she's given to a business publication. "The only time I think about being a businesswoman is now, while I'm talking to you. There's this part of me that's afraid of what will happen if I believe it all."

You'd be hard pressed to find another American chief executive this disarming, this confessional. But it's oh-so-Oprah. Sitting in an overstuffed armchair in her office in Harpo Inc.'s Chicago headquarters, her two cocker spaniels lying at her feet, the chairman swears that if she is a businesswoman, it's in spite of herself. She happily admits that she cannot read a balance sheet. She has no corporate role models. She's kissed Tom Cruise and more than one world leader, but she has never even met Jack Welch or Michael Dell. She's declined invitations from AT&T, Ralph Lauren, and Intel to sit on their corporate boards. "I just say, 'Guys, I don't know what I'd be doing on your board.' " And she's so wary of investing her own money in the stock market that she once hoarded $50 million in cash, calling it her personal "bag-lady fund."

Winfrey--we'll call her Oprah, just because everybody else does--is kidding herself. Despite her protestations, she is at the helm of a mighty successful business. At its foundation is The Oprah Winfrey Show with its 22 million U.S. viewers, but she's been branching out into movie production, cable TV, magazines, and the Internet. She's at the peak of her power--and frankly, she's confused. In the fall she told FORTUNE that she was "at a crossroads. Not a crisis, but a juncture." Over the next few months she seemed reinvigorated but was still waffling about where she was headed. Then in mid-March, as this story was going to press, Harpo disclosed that Oprah would quit her show after the 2005-06 season, her 20th year in talk TV. "I like even numbers," says Oprah. And she wants to go out on top.

Take that statement for what it's worth. Oprah has publicly contemplated quitting her show before and is notorious for spur-of-the-moment decisions. But if she does follow through on this plan, the disappointment will surely spread beyond her show's loyal viewers. Walt Disney President Bob Iger, whose ABC network airs her syndicated show in most major markets, says Oprah contributes "tremendous profits" to Disney, thanks to ad sales and the lead-in lift she gives to the network's schedule. In the book-publishing industry, where margins are tight, an Oprah endorsement can make all the difference. Dick Parsons, CEO-designate of AOL Time Warner (which owns Warner Books as well as Time Inc., FORTUNE's publisher), says that the Oprah's Book Club insignia on a novel typically pumps up sales tenfold. No Oprah, no megaphone to trumpet the books.

The Oprah show is clearly the core of her business, contributing the lion's share of revenues--some $300 million last year--to Harpo. It airs in 107 countries and has held its No. 1 spot in U.S. daytime talk for 16 years despite challenges from at least 50 rivals. It's a mass-market megahit that appeals to the middle-aged, middlebrow audience that advertisers such as Procter & Gamble, Sears, and Wal-Mart are eager to reach. But it's hardly her only venture.

Her two-year-old magazine, O, The Oprah Magazine, is the most successful startup ever in the industry. Last year it raked in more than $140 million in revenues. According to her joint-venture partner, Hearst Magazines President Cathleen Black, it is "significantly profitable," a remarkable feat given that successful magazines generally take five years to turn a profit. In an advertising recession so tough that titles such as Mademoiselle and Talk have disappeared, O's ad sales actually rose 43% in the first four issues of the year, compared with the same four last year. The magazine reaches a richer set of fans than those watching the daytime TV show. O readers have an average income of $63,000 and lean towards brands like Lexus, Donna Karan, and Coach. And they seem to love this "personal-growth manual," as Oprah describes the monthly; O has a paid circulation of 2.5 million, more than Martha Stewart Living or Vogue--or this magazine, if you must know.

Her movie production division turns out award-winning television films like Tuesdays With Morrie and brings in about $4 million a year. Her "guru" business last year generated $1.6 million in ticket sales as 8,500 women in four cities paid $185 each to hear Oprah deliver her gospel of self-affirmation on her "Live Your Best Life" tour. She also holds a substantial stake in Oxygen Media, a cable TV company for women, for which she produces and stars in a show called Use Your Life.

Forced by this reporter to listen to this litany of accomplishments, Oprah tucks her loafered feet into the cushion of her big chair and fesses up. "Yeah," she acknowledges, "I guess I am a businesswoman." A businesswoman, however, with a lot of other ideas spinning around her brain.

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