A Cairo appeals court on Sunday acquitted 64 non-Islamist protesters on charges of illegal assembly and rioting.
The defendants – 68 in total – were previously sentenced to two years in prison and had appealed the ruling.
The remaining four defendants, all students, didn't attend Sunday's court session as they were sitting for their exams. Their ruling has been postponed to 6 July.
The defendants were arrested in clashes in Cairo's Al-Azbakeya district on 25 January, the third anniversary of the 2011 uprising which unseated the autocrat Hosni Mubarak.
Hundreds of protesters, including prominent activists, have been handed hefty jail terms and fines since Egyptian authorities passed a strict protest law last November banning all demonstrations not pre-approved by the police.
Sunday's ruling is rare, as very few defendants' appeals have resulted in acquittal.