Last week, U.S. fiction publishers heard to their dismay that they are about to lose the single biggest booster their industry has known in the past six years: television talk-show host Oprah Winfrey's astonishingly influential monthly book club. True, the same period also saw the advent of "Harry Potter" author J.K. Rowling -- another major gift to the global book industry. But Ms. Rowling really only inspired people to buy and read "Harry Potter" and its sequels; Ms. Winfrey inspired them to buy and read, in their tens of millions, a whole assortment of books they might otherwise never even have heard of.

There were 46 of them over the years -- from the first, Ms. Jacquelyn Mitchard's tearjerker "The Deep End of the Ocean," to the last, this month's intellectually demanding "Sula," by Ms. Toni Morrison -- and every single one became a U.S. best seller, most of them solely on the strength of Ms. Winfrey's say-so. Not just any old best seller, either: The majority of "Oprah picks" have sold around 1 million copies, some of them four times as many, whereas the usual high-water mark of success for a U.S.-published novel is 30,000. Most, of course, chalk up far fewer sales than that.

Many of Ms. Winfrey's selections have also sold much better overseas following their home-turf success. Would Ms. Barbara Kingsolver's excellent but difficult novel "The Poisonwood Bible," for example, ever have been translated into Japanese without the Oprah imprimatur? No wonder publishers are feeling rueful about Ms. Winfrey's decision to withdraw from the book-recommendation game.