The war crimes trial of John Demjanjuk, 89, was adjourned by a German court Thursday after the accused complained of feeling unwell, DPA reported.
The Ukrainian-born man told doctors in prison he was feeling tightness in the chest, Presiding Judge Ralph Alt said.
Demjanjuk, who spent most of his life in the United States, is accused of taking part in the death-camp murders of 27,900 Jews during 1943 at Sobibor death camp in Nazi-occupied Poland.
Doctors in the hospital ward of Stadelheim Jail then recorded an electro-cardiogram of his heartbeat and confirmed some fibrillation but nothing else untoward. Judge Alt said the court could have ordered Demjanjuk to attend, but would not exercise that power.
After the trial began in later November, there was a long adjournment while Demjanjuk recovered from a cold.
To date, Demjanjuk has lain on most days in court on a wheeled stretcher with his mouth open, as if he were short of air. He regularly pulls his trademark blue cap over his face, to avoid being dazzled by ceiling lights, according to his lawyers.
Throughout the trial so far the normally chatty former Ohio factory worker has not spoken, though he was animated on Tuesday outside the courtroom, quipping to a German television team, "What's up? I'm not Hitler!"
The war crimes trial - which has attracted worldwide attention - is expected to be one of the last from the Nazi-era.