The trial of Egyptian Muslim Brotherhood chief Mohammed Badie and his two deputies on charges of inciting the murder of protesters was adjourned minutes after it opened Sunday because the defendants were absent.
The Brotherhood leaders and 32 other Islamist defendants were not brought to court for security reasons, security officials said.
The three leaders of Egypt's Muslim Brotherhood and the movement's former arch-foe Hosni Mubarak were scheduled to face separate trials on Sunday on similar charges of involvement in the killing of protesters.
With Egypt now under an army-installed government after last month's overthrow of Islamist President Mohammed Mursi, local media seized on the symbolism of scheduling both sessions on the same day. "Trial of two regimes," headlined al-Shorouk daily.
The case against Mohammed Badie, the Brotherhood's "General Guide," and his deputies, Khairat al-Shater and Rashad Bayoumy, relates to unrest before the army removed Mursi on July 3. Mursi has been detained in an undisclosed location since then.
Mubarak, who left prison on Thursday after judges ordered his release, was due to attend his session with his jailed sons Gamal and Alaa and former Interior Minister Habib al-Adly.
The former president was sentenced to life in prison last year for complicity in the killing of protesters during the revolt against him, but an appeals court ordered a retrial.
The state news agency MENA said a helicopter would fly Mubarak to the court hearing in the Police Academy on the eastern outskirts of Cairo from a military hospital where he was placed under house arrest after his release from jail.
The government used a state of emergency it declared earlier this month to place Mubarak under house arrest, apparently to forestall any popular anger if he had simply walked free.
The trial of the Brotherhood's top leaders signals that Egypt's new army-backed rulers intend to crush what they have portrayed as a violent, terrorist group bent on subverting the state.
The Brotherhood, which won five successive post-Mubarak votes, says it is a peaceful movement unjustly targeted by the generals who ousted Mursi, Egypt's first freely elected leader.
The military contends it was responding to the people's will, citing vast demonstrations at the time against the rule of a man criticized for accumulating excessive power, pushing a partisan Islamist agenda and mismanaging the economy.
Charges against Badie and his aides include incitement to violence and relate to an anti-Brotherhood protest outside the group's Cairo headquarters on July 30 in which nine people were killed and 91 wounded. The 70-year-old Brotherhood leader was detained last week. Shater and Bayoumy were picked up earlier.
More than 1,000 people, including about 100 soldiers and police, have died in violence across Egypt since Mursi's fall, making it the bloodiest civil unrest in the republic's 60-year history. Brotherhood supporters say the toll is much higher.