A microbus driver died on Saturday during clashes between police and pro-Muslim Brotherhood protesters in Giza's Faisal district, one day before the fourth anniversary of the 25 January uprising.
Driver Wassim Abdel-Gaber, 43, was passing the scene and was not involved in the protests, Al-Ahram Arabic website reported.
Al-Ahram reported that he had died of possible gunshot wounds.
On Friday, a teenage girl died from a birdshot wound during the police's dispersal of a pro-Morsi protest in Alexandria.
Sunday 25 January marks both national police day and "revolution day". The day is a national holiday, but scheduled celebrations were cancelled to mourn the death of Saudi's King Abdullah.
Supporters of the Muslim Brotherhood, which was banned by the government and declared a terrorist organisation, have staged regular protests since Morsi's 2013 ouster.