An explosion struck inside St. George church in the Nile Delta city of Tanta, killing at least 27 people and injuring scores, the Health Ministry said in a statement.
Hours later, 13 people were killed and dozens injured when a suicide bomber blew himself up at a security checkpoint outside St. Mark’s Cathedral in the coastal city of Alexandria.
In a statement, the Interior Ministry said a bomber detonated himself after being prevented from breaking through the security cordon around the church.
It confirmed that four policemen were among those killed in the attack.
A church source said Coptic Pope Tawadros II was inside the church when the bombing took place but he was unhurt.
Daesh terrorist group has claimed responsibility for the attacks via its Amaq news agency.
Sunday’s bombings occurred on Palm Day, a Christian feast commemorating the entry of Jesus Christ into Jerusalem.
In December, a bomb blast struck a church in central Cairo, killing more than 25 people and injured scores.
Coptic Christians are estimated to account for between 8 and 10 percent of Egypt's population of about 90 million.