Zschaepe is charged with complicity in the murders of eight ethnic Turks, a Greek immigrant and a German policewoman. She is also accused of involvement in 15 armed robberies, arson and attempted murder in two bomb attacks.
She faces life in prison if convicted. Four men, alleged accomplices, will also go on trial on lesser charges.
The German security agency, much criticised for failing to stop the NSU murder spree, estimates that there were 22,400 far-right extremists, including 9800 who had voiced or shown a willingness to use violence, in late 2011.
They are organised into over 200 clandestine groups with names such as "National Socialist Hatecore" and the international "Blood & Honour" network, said the latest report by the Federal Office for the Protection of the Constitution.
Because Nazi symbols are banned, many extremists now wear black hooded sweaters, baseball caps, scarves and sunglasses, making them difficult to distinguish from their traditional arch-enemies, the left-wing anti-fascist activists.
- AFP