Piven was nominated for a Golden Globe for Entourage
Producers of Broadway play Speed-the-Plow have filed a grievance with the stage actors' union Equity against Entourage star Jeremy Piven.
The actor quit the show suffering from mercury poisoning, which his doctor said was possibly caused by eating large amounts of raw fish.
It has been reported producers want Equity to carry out an independent evaluation into Piven's health.
Piven's publicist, Samantha Mast, called the claims "absurd".
She added that the 43-year-old actor quit due to "medical necessity on the advice of his doctors, after he was hospitalised".
His doctors said he had six times the normal level of mercury in his body.
The Emmy-award winning star, who plays agent Ari Gold in Entourage, has been the target of jokes since leaving the play.
Speed-the-Plow writer David Mamet even quipped: "My understanding is that Jeremy is leaving showbusiness to pursue a career as a thermometer."
The actor defended his departure on American television, telling ABC's Good Morning America: "I've never not completed anything in my life...I wanted the show to continue forever."
William H Macy has now stepped into Piven's role in the production.
It is not yet known if the show's producers are seeking financial compensation from the actor.