The doctor says the protester died of wounds from birdshot fired at close range outside the Interior Ministry in downtown Cairo. He spoke on condition of anonymity, fearing for his life.
The death brings to three the number of those killed Friday in Egyptian street protests. Two protesters died earlier in the day in Suez.
The protesters blame police and the country’s military rulers for failing to halt violence after a Wednesday soccer game in Port Said that killed 74 people.
A photograph of the protester killed in Cairo was posted online by a man who took him to a hospital where he was declared dead.