The trials began Sunday of 55 suspected al-Qaida members, some charged in a deadly attack on a U.S. Consulate in 2004, the kingdom's official news agency reported.
The Saudi Interior Ministry said eight people were killed in the 2004 storming of the consulate in the port city of Jeddah, including three militants and five citizens of Arab countries who worked at the consulate. A fourth militant died later.
In the brazen attack on Dec. 6, 2004, militants lobbed grenades at the heavily guarded consulate, attacking staffers and holding some hostage in the compound before Saudi security forces stormed in.
Al-Qaida in the Arabian Peninsula, believed to be one of the terror network's most active branches, claimed responsibility for the attack, saying it was part of its war aimed at forcing non-Muslims out of the area.
Saudi Arabia is home to Islam's two holiest sites, Mecca and Medina.
A statement on a militant website at the time said the attack was also in retaliation for the U.S. invasion of Iraq and one the war's bloodiest battles, in the city of Fallujah.
The Saudi Press Agency reported that six men came before the court Sunday, and the trial of another three began a day earlier. The report did not say when the rest of the 55 would be tried, or how many of them were accused in connection with the consulate attack.