The pair were due to continue their bitter rivalry in Manchester on October 29 for a fight that had already been called off once due to an injury to Fury.
The Brit won the WBA and WBO heavyweight titles from Klitschko last November, but has since had to deal with doping allegations and a loss of fitness.
Fury's camp have now confirmed that the champion is "medically unfit to fight" after what is understood to be a training camp injury setback, and as a result the bout has been pushed back once again.
"It is with the deepest regret that we have to announce that the world heavyweight championship rematch between Tyson Fury and Wladimir Klitschko, scheduled to take place on October 29, 2016 at the Manchester Arena, will not be going ahead," a statement read.
"Tyson has, this week, been declared medically unfit to fight. Medical specialists have advised that the condition is too severe to allow him to participate in the rematch and that he will require treatment before going back into the ring. Tyson will now immediately undergo the treatment he needs to make a full recovery.
"We and Tyson wish to express our sincerest apologies to all those concerned with the event and all the boxing fans who had been looking forward to the rematch. Tyson is understandably devastated by the development."
Fury last week failed to show up to a press conference between the pair, citing car trouble as the reason.