Leno left his office at NBC's studios about midday and checked himself into a hospital for observation, said his publicist, Dick Guttman. He would not identify what ailed Leno, but characterized it as "mild" and said the comedian continued to work Thursday, making phone calls and writing jokes.
"Jay Leno is doing just fine," read a statement from NBC spokeswoman Tracy St. Pierre. "He was kidding around with the hospital staff and running his monologue jokes by the doctors and the nurses. He's expected back to work on Monday."
A woman who answered the news and communications line at Providence Saint Joseph Medical Center, which is near the Burbank studio where Leno tapes "Tonight," said they had no patient by the name of Jay Leno, and referred inquiries to NBC.
Scheduled guests on Thursday's show were Ryan Reynolds, Jules Sylvester and the swing band Big Bad Voodoo Daddy. Instead, NBC planned to air a rerun.
It was an unusual lapse for the famously intrepid performer, who routinely fills off-days from his TV show with live appearances on the comedy circuit.
Leno, who turns 59 on Tuesday, will leave the "Tonight" show May 29 after 17 years. But he will continue on NBC, with a Monday-through-Friday program at 10 p.m., starting in the fall.
The top-rated late-night host's move to prime time created a stir in the industry, taking the time slot usually reserved by broadcast networks for dramas such as "ER." And Leno has continued to make news, scoring a coup by booking President Barack Obama as a guest and performing free comedy concerts in the recession-wracked Detroit area.
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