It is the fourth time Germany has attempted to put 95-year-old Hubert Zafke on trial.
His ill health has repeatedly forced proceedings to be postponed.
Mr Zafke is charged with 3,681 counts of accessory to murder at the Nazi death camp.
He was pushed into Neubrandenburg state court in a wheelchair on Monday, holding a wooden cane in his hand.
According to Germany’s dpa news agency, he made no comment after the charges against him were read out.
His attorney argues he did nothing criminal.
The trial, initially set to begin in February, was postponed by presiding Judge Klaus Kabisch on three occasions after a doctor’s assessment found Mr Zafke was not well enough to participate.
It comes three months after a former Auschwitz guard was jailed for five years for complicity in 170,000 murders at the Nazi death camp.
Reinhold Hanning, 94, served at the camp in Poland during the Second World War between January 1942 and June 1944.
News Source SkyNews