Applegate shared her news with her 1.4 million followers on Twitter.
"Hi friends. A few months ago I was diagnosed with MS. It's been a strange journey", she wrote.
"But I have been so supported by people that I know who also have this condition".
"It’s been a tough road. But as we all know, the road keeps going. Unless some a****** blocks it".
"As one of my friends that has MS said " we wake up and take the indicated action". And that's what I do. So now I ask for privacy. As I go through this thing. Thank you xo".
Several stars have revealed that they have been diagnosed with M.S. These include Sopranos star Jamie-Lynn Sigler, Applegate's co-star from The Sweetest Thing Selma Blair as well as talk-show host Montell Williams.
Christina Applegate had been previously diagnosed with breat cancer in August 2008. She shared that she was cancer free, having undergone a double mastecomy a month later.