Demjanjuk landed in a specially-chartered plane at Munich airport after flying out late Monday from Cleveland's Burke Lakefront Airport.
The 89-year-old Ukrainian-born man, who his family says is seriously ill, was expected to have the charges against him read out on his arrival and then be transferred to the nearby Stadelheim prison, where he will undergo a medical examination.
He could even be brought face-to-face with a surviving witness from the Sobibor death camp in Nazi-occupied Poland, where he was a guard in 1943, German television said.
This witness, 82-year-old Thomas Blatt, described the conditions at Sobibor which the US Office for Special Investigations (OSI), was "as close as approximation of Hell as has ever been created on this Earth."
In an interview with Der Spiegel magazine, Blatt said: "They abused us. They
shot new arrivals who were old and sick and could not go on. And there were some who pushed naked people into the gas chambers with bayonets."
"Sobibor was a factory. Only a few hours passed between arrival and theburning of a body," Blatt added.
Demjanjuk has always insisted that he was forced to work for the Nazis and has been mistaken by survivors for other cruel guards. His son John wrote Monday: "Given the history of this case and not a shred of evidence that he ever hurt one person let alone murdered anyone anywhere, this is inhuman even if the courts have said it is lawful."
"This is not justice, it is a vendetta in the falsified name of justice with the hope that somehow Germany will atone for its past," said his son.
But Demjanjuk is right at the top of Nazi hunters' most-wanted list. He was suspect number three in the Simon Wiesenthal Centre's latest report on Nazi war criminals - behind two others thought already dead.
The group's founder Rabbi Marvin Hier noted that if Demjanjuk comes to trial it "will probably be the last trial of a Nazi war criminal."
However, Stephan Kramer, general secretary of the German Jewish Council, said he did not believe Demjanjuk would be jailed.
"I am not so naive to think that he will spend a single day in prison," Kramer told German television channel N24.
"But we will at least have a discussion about German post-war justice and how they deal with Nazi criminals ... In this sense, it is good and right that he was deported to Germany and will be placed before a court here," he added.
If he did appear before the court, it would be the second time he has faced such charges.
He was condemned to death in Israel in 1988 after he was convicted of being the sadistic Nazi guard nicknamed "Ivan the Terrible," who would hack naked prisoners to death with a sword.
However, the verdict was overturned by Israel's Supreme Court in 1993 when statements from former guards identified another man as "Ivan the Terrible."
Blatt said: "I do not care whether he goes to prison or not. It is the trial that is important to me. I want the truth. People need to know what it was like at Sobibor."