The ‘Tonight Show’ anchor, Jay Leno had been hospitalized with an undisclosed illness. ‘Tonight’ show, taping had been cancelled but was doing well and planned to return next week, his publicist and NBC said.

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 characterised it as ‘mild’ and said the comedian continued to work on Thursday, making phone calls and writing jokes.

The network planned to air a rerun of the show Thursday night.

Scheduled guests were ‘X-Men Origins: Wolverine’ actor Ryan Reynolds, celebrity animal trainer Jules Sylvester and Big Bad Voodoo Daddy.

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 programme, starting in the fall.