Warner Wolf, 80, charges in the lawsuit filed Thursday that he was illegally fired in 2016 because of his age. The lawsuit says Imus once said it was time to put Wolf "out to pasture" and "shoot him with an elephant-dart gun."
The lawsuit filed in New York state Supreme Court names Imus and three executives with WABC radio and its parent company Cumulus Media as defendants.
A spokesman for Imus says he declines comment. A spokeswoman for Cumulus says the company isn't commenting.
The 77-year-old Imus has announced that his show will go off the air on March 29.