Judge Thokozile Masipa asked for the recess, saying an assessor is ill, which means the court is not properly staffed.
The defence team was scheduled to start presenting its case on Friday, as the state had wrapped up its arguments earlier this week.
Pistorius was widely expected to take the stand Friday as the defence's opening witness.
Defence lawyer Brian Webber told the Associated Press it was "likely" Pistorius would be the defence's first witness. It is normal practice for the accused to testify first.
Pistorius, the 27-year-old blade runner, is accused of murdering his girlfriend, model Reeva Steenkamp, in the early hours of Valentine's Day last year.
Pistorius maintains he killed 29-year-old Steenkamp by accident, believing she was an intruder in his home.
Pistorius was seen leaving the courtroom shortly after the session.