The union, which announced a strike for September before postponing the action to allow for more talks, is angry at league demands that unwanted players train away from the first team squads or accept a transfer even when under contract.
Last-ditch talks with Serie A and the Italian football federation in Rome failed to reach an agreement ahead of the union's November 30 deadline.
"The strike has been called for December 11 and 12. We are very sad because there was a willingness to find an agreement," union vice president Leonardo Grosso told reporters, adding that they would soon issue a statement confirming the strike.
"The league continued to ask to discuss the issue of players being placed outside of the squad, which for us was case closed."
The federation hoped the union would wait for an Olympic Committee hearing on Wednesday before calling a strike, and like so often in Serie A there may still be a twist in the tale.
Italian football has endured a match-fixing scandal, hooligan problems and two failed European championship bids in recent years, with decaying stadiums and low attendances adding to a sense of apathy relieved only by sporadic on-field success.
Serie A players have gone on strike in the past over similar issues, and the threat of games such as Juventus v Lazio being called off now hangs over the league, although champions Inter Milan will be away at the Club World Cup that weekend.
INDEPENDENT BODY
Serie A, in its first season as an independent body having broken away from the Italian league, has been negotiating a new collective contract with the union over basic players' rights.
The original contract expired in the close season without any agreement, and the dispute has rumbled on ever since.
Some players such as AC Milan right-back and Italy World Cup winner Massimo Oddo, who proclaimed the original strike, have since said striking is a bad idea, but the union leadership has carried on regardless.
Serie A president Maurizio Beretta, who still hopes a deal will be struck, told reporters: "Today's meeting was incredible, without precedence in history.
"The union refused to listen to the federation president's intervention, which included the issue of players outside the squad. At that point they got up from the table and left."
Media have criticised multi-millionaire players for considering a strike during a time of economic hardship, but the union can point to three cases that support their stance.
Juve's Fabio Grosso and Hasan Salihamidzic were dropped at the start of the season for turning down transfers but an injury crisis meant they were brought back.
Goran Pandev was banished by Lazio last term for demanding a move but an arbitration panel ruled in his favour and he signed for Inter on a free, a case that may have implications for Sampdoria's Antonio Cassano and Cagliari's Federico Marchetti.
Cassano and Marchetti have both been dropped for disciplinary reasons and arbitration
