Those sentenced to death include senior Brotherhood leaders Essam al Erian and Mohamed Beltagi and prominent preacher Safwat Higazi. Mahmoud Abu Zaid, a photojournalist known as "Shawkan," was handed five years imprisonment.
Egypt sentenced to death 75 people, including prominent leaders, on Saturday over a 2013 pro-Muslim Brotherhood sit-in which ended with the killing of hundreds of protesters by security forces.
Others being tried in the case, including Brotherhood spiritual leader Mohamed Badie, were handed life sentences, judicial sources said.
TRT World's Arabella Munro reports.
Those being sentenced are accused of security-related offences including incitement to violence, murder and organising illegal protests.
Rights groups have criticised the mass trial of more than 700 people in what has become known as the Rabaa case, after Rabaa Adawiya square where the sit-in took place in Cairo.
Those sentenced to death by hanging include senior Brotherhood leaders Essam al Erian and Mohamed Beltagi and prominent preacher Safwat Higazi, the sources said.
The dispersal of the sit-in in August 2013 came weeks after President Abdel Fattah el Sisi, then military chief, ousted president Mohamed Mursi after protests against Brotherhood rule.
Amnesty International says more than 800 protesters were killed. The government has said many protesters were armed, and that 43 police were killed.
Since Sisi took power in 2014, authorities have justified a crackdown on dissent and freedoms as being directed at terrorists and saboteurs trying to undermine the state.
Death sentences have been handed down to hundreds of his political opponents on charges such as belonging to an illegal organisation or planning to carry out an attack.