0326 GMT June 20, 2018
Mass trials have been common since the army deposed former president Mohamed Mursi in 2013 following nationwide demonstrations. Both local and international rights groups have repeatedly voiced criticism, Reuters wrote.
The 43 defendants had been charged with rioting, vandalism and attacking security forces during clashes with police and the army in Cairo in December 2011, in which at least 17 people were killed and almost 2,000 were wounded.
The defendants were also fined more than 17 million Egyptian pounds ($948,661) combined for vandalizing public property during the clashes.
Nine others were sentenced to 10 years in prison and one to five years, while 92 were acquitted, in the case that was dubbed by local media "cabinet clashes", a reference to the cabinet building where the unrest occurred.
The defendants can appeal their verdicts to a higher court. Life sentences in Egypt last 25 years.
The case was retried because initial verdicts in 2015 had been issued while the defendants were in abstentia.
The clashes broke out near the cabinet and parliament buildings in the Egyptian capital months after the Arab Spring uprising that ousted former Egyptian President Hosni Mubarak.