Spanish giants Real Madrid and Atletico Madrid have been banned from registering players for the next two transfer windows.
They have been punished by world governing body FIFA for breaching rules over the transfer of minors.
The ban does not cover the current transfer window, which runs until the end of this month.
Atletico were fined 900,000 Swiss francs (£622,000), while Real were told to pay 360,000 (£249,000).
There were no immediate comments from the clubs, which have the right to appeal against the decision.
Barcelona were given the same penalty in April 2014 for also breaching rules on the transfer of under-18 players.
The next two transfer windows are July/August 2016 and January 2017