Pope Francis and Pope Tawadros, the heads of the Roman Catholic and Coptic Orthodox churches respectively, signed on Friday an agreement announcing that both churches would acknowledge the baptisms of each other.
The text of the agreement said that the two popes "will not seek to repeat the baptism that has been administered in either of our Churches for any person who wishes to join the other."
The Coptic Orthodox Church had previously required new members who were joining from the Catholic church to undergo a new baptism.
Pope Francis arrived in Cairo on Friday for a historic two-day visit, the first such papal trip to the country since Pope John Paul II in 2000.
Francis met with Tawadros as well as President El-Sisi, and addressed a conference on peace for religious leaders being held at Al-Azhar.