David Irving has been in custody in Austria since November. He was detained on charges stemming from two speeches he gave there in 1989 in which he allegedly denied the Nazis' extermination of some 6 million Jews.
An eight-member jury and a panel of three judges will hear the proceedings, which officials said could produce a verdict as early as today.
His trial opens amid a debate over freedom of expression in Europe, where the printing and reprinting of unflattering cartoons of the Prophet Muhammad has triggered violent protests worldwide.
Remembering The Holocaust
Children from the Auschwitz death camp when it was liberated in 1945 (epa)
Ceremonies were held around the world on January 27 to remember the victims of the Holocaust. It's the first international day commemorating the mass murder of Jews during World War II, and it falls on the anniversary of the 1945 liberation of the Nazi death camp at the site of the Auschwitz-Birkenau death camp in Poland. RFE/RL correspondent Kathleen Moore has assembled an audio portrait for the occasion, in which you'll hear voices of camp survivors, as well as sounds from the 60th anniversary commemorations at Auschwitz last year. It starts with the screech of brakes, recalling the trains that once took people to their deaths at Auschwitz.
Music and singing from 60th anniversary ceremony
Survivor Anita Lasker-Wallfisch in English: "We knew what was going on in Auschwitz, so it was a matter of preparing yourself to be stuck in a gas chamber."
Survivor Halina Kastrytskaja in Russian: "A train with Jews had arrived just before our train came [to the camp]. As the train with the Jews was unloaded they were taken straight to the crematorium."
Archive news announcer in English: "…the Nazi plan for the physical extermination of the Jews known as the Final Solution of the Jewish problem...."
Survivor Kurt Goldstein in English: "Three years that I passed in this camp which was a hell on earth."
Survivor Roman Kent in English: "How can one document the smell of burning flesh which filled the air? How can one describe the living skeletons, still alive, just skin and bones?"
Waldemar Dabrowski, Polish culture minister in 2005, in Polish: "We are on the site of the most gigantic cemetery in the world, a cemetery where there are no graves, no stones, but where the ashes of more than 1.5 million beings lie."
U.S. Vice-President Dick Cheney in English: "On this day in 1945, inside a prison for the innocent, liberators arrived and looked into the faces of thousands near death."
Russian President Vladimir Putin in Russian: "We bow our heads before the victims of the Holocaust, before all the victims of the inhumane war unleashed by Nazism. We mourn them and remember the immortal feat of the anti-Hitler coalition."
Unidentified female survivor in Polish: "Never -- never will this happen again."
Israeli Nobel Peace Prize winner Elie Wiesel in English: "If you, after this day, will be the same, then we have lost an encounter with this memory which you are now the custodians of, it must do something to you and through you the whole world and put an end to the curse of hatred and the scourge of anti-Semitism, racism, bigotry, hatred.''
United Nations Secretary-General Kofi Annan in English: "The evil that destroyed 6 million Jews and others in those camps is one that still threatens all of us today. Every generation must be on its guard to make sure that such things never happen again."
Paul Wolfowitz, then U.S. deputy defense secretary, in English: "Never again and never forget."
(compiled from RFE/RL interviews and archive materials)
A women's barracks at Auschwitz in 1945 (epa)
To view a microsite devoted to RFE/RL's coverage of the 60th anniversary of the end of World War II, click here.