Egypt's juvenile misdemeanour court on Wednesday sentenced 78 youth, allegedly supporters of ousted president Mohamed Morsi, to jail terms of three to five years.
The minors – aged between 15 to 17 years old – were accused of rioting and belonging to a terrorist group.
The Muslim Brotherhood, from which Morsi hails, was labelled a terrorist organisation by Egypt's authorities last year.
The minors were arrested in demonstrations in the Mediterranean city of Alexandria soon after the 14 August 2013 dispersal of the two biggest pro-Morsi sit-ins in Cairo, in Rabaa and Nahda squares, which left hundreds dead and sparked nationwide unrest.
Egypt passed a controversial protest law in November 2013 that activists have deemed restrictive as it bans unauthorised demonstrations.
Thousands have been arrested under its provisions, from Brotherhood members to secular activists.