Former Radio 1 DJ Mark Goodier has suffered a stroke, his production company said.
Goodier - who presented the Sunday night chart show for around 10 years until 2002 - is recovering at home following the illness at the beginning of November.
An out of office reply to his email address at production company Wisebuddah said: “Thank you for your email.
“I am away from work for a time recovering from a stroke and so not seeing email every day.”
The 55-year-old is receiving “excellent” medical attention and expected to return to work before the end of December, Wisebuddah said.
Goodier’s recovery means he is unable to record the voiceover for a television advert for Now 95 - a job he has done since Now 20 was released in 1991.
The advert will be voiced by Xtra Factor’s Matt Edmonson in his place.