April Fool's days is a centuries-old Western tradition, perhaps best appreciated by mischievous 10-year-old boys.

So no one in the business world would want to mess around with pranks, right? Isn't there already enough misinformation and rumors racing around the marketplace without adding to the confusion?

Oh, you might be surprised by what comes out today.

Already one news organization has been briefly fooled this year. Crain's Chicago Business last week carried a report online about Donald Trump acquiring a controlling interest in Time Out Chicago. Crain's was taken in by a press release and the cover of the magazine's March 27-April 2 issue, which features a grinning Donald on the cover with the headline "Our New Owner." The magazine has a letter purportedly from him, saying that the new Time Out Chicago "is going to be huge, absolutely huge."

"We thought people would realize this was a parody issue," Tony Barnett, marketing director for Time Out Chicago, told Crain's after the fact. "That's why we didn't send out the press release without the magazine."

Bigger publications can also be taken in. In 2002, the Wall Street Journal interpreted a March 31 statement from Mohammed al Fayed, owner of Harrods, that he was planning to float the luxury London department store to mean that he was going to take it public, in British financial parlance. The release was actually pretending that Harrods would float in the Thames, and the purported press contact was Loof Lirpa (April Fool backward).

Al Fayed was apparently pleased with the joke, but failed to be amused when the Journal, after running a correction, gave its own tongue-in-cheek response a few days later, with a brief article about the gimmick and the publicity it generated under the headline "The Enron of Britain?" Harrods brought a libel action in London, a case that it lost in 2004.

Spoofs can backfire in different ways. Google has had prank releases in previous years, such as last year's announcing the Toilet Internet Service Provider. So it wasn't perhaps the smartest idea in retrospect to introduce its Gmail email service on the eve of April 1, 2004.

Even people who should know better have had their foolish moments. Last year, the Securities and Exchange Commission issued a press release contending that it would require public companies to disclose the 100 employees who make more than the C.E.O. The spokeswoman listed on the release was April Fuhrst.

When it comes to advertising, some companies have felt free to be more playful on this day. The best known may be the full-page ads that Taco Bell took out in 1996, saying that it had bought the Liberty Bell to help reduce the national debt.

But others clearly don't care about the tradition. At least a dozen U.S. companies won't be fooling around today: they are reporting quarterly results.

Jeffrey Cane