Judges said in a written decision the adjournment is "in the interests of justice" and will run from March 21 to May 5. The trial continues as scheduled until the break.
Karadzic, who is defending himself, complained last month that prosecutors had dumped 32,000 pages of evidence and some 200 hours of video on him - too much for him to review while the trial was going on.
Karadzic faces 11 war crimes charges, including two genocide counts, for allegedly masterminding Serb atrocities throughout the 1992-1995 Bosnian war. He insists he is innocent.
The delay is the latest setback for the slow-moving trial that began in October 2009 but was halted almost immediately when Karadzic boycotted proceedings, saying he had not had enough time to prepare. The first witness was heard last April.
Judges suspended Karadzic's trial for a month in November for the same reason and rebuked prosecutors for late disclosure of evidence.
In Wednesday's decision, judges again expressed "deep concern" about the volume of evidence prosecutors continue to disclose to Karadzic "and the impact which this has had on the accused's preparations and the smooth conduct of this trial."
Judges have warned that the trial could stretch into 2014 - two years longer than expected - if prosecutors and Karadzic don't speed up. Judges largely blame Karadzic, saying he often takes three times longer to cross-examine witnesses than prosecutors take to question them.