German doctors say John Demjanjuk is in better shape than the average 89-year old and fit enough to remain in jail as he awaits charges.
Demjanjuk arrived in Germany on Tuesday.
Doctors who examined the suspected former Nazi death camp guard after his arrival at the Stadelheim jail in southern Munich on Tuesday, determined that he is fit to remain in custody to face charges that he helped kill 29,000 Jews in the Sobibor extermination camp in 1943.
"John Demjanjuk is in strikingly good condition," said Jochen Menzel, the deputy director of the Stadelheim jail in southern Munich. "He is not typical for his age, he is in better shape than usual for an 89-year-old," Menzel told German TV news channel N24.
Doctors are now to conduct tests to determine whether the Ukrainian- born man is fit enough to undergo the stress of what is expected to be a long trial. A decision is expected in about two weeks' time.
This video image taken by US officials last month shows Demjanjuk, who was fighting deportation on grounds of ill health, getting into a car.
Family loses Demjanjuk deportation appeal
Demjanjuk's family in the United States lost the battle this week to prevent his deportation to Germany. They had insisted he was too sick to travel and suffers from spinal problems, kidney failure and anaemia.
The 89-year-old Demjanjuk is currently stateless. The US stripped him of his citizenship for lying about his past. Munich prosecutors say he is being tried in the Bavarian capital because he had been registered as living there after World War II.
Demjanjuk tops the Simon Wiesenthal Center's list of its 10 most-wanted suspected war criminals. This court case could be Germany's last major Nazi trial.
Demjanjuk's lawyer says his client says he was never in the Sobibor camp.