Barcelona’s summer signing Luis Suarez, Belgium defender Thomas Vermaelen, France defender Jeremy Mathieu and Croatia midfielder Ivan Rakitic.
could be the last by the Catalan outfit until January 2016.
The La Liga side has failed in its latest attempt to have a transfer ban lifted.
FIFA, the sports governing body has announced it has rejected an appeal by the club.
Barcelona had been given a 14-month ban for being found guilty of having breached rules on signing international players under the age of 18.
The club appealed and that ruling was suspended allowing the capture of the players in the summer
The latest ruling will not come into force until the next transfer window so the summer signings are not affected.
It also means the club could sign more players before this transfer window closes on August 31.
Barcelona reacted with a statement saying it would “continue defending its interests before the highest sporting authority, in this case the Court of Arbitration for Sport.”