Former Radio 1 DJ Mark Goodier has suffered a stroke, his production company said.
Mark - 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 confirmed.
Mark's recovery means he is unable to record the voiceover for 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.