In the first accident, at least 10 people were killed and 20 others injured after scores of vehicles, including private cars and microbuses, collided due to heavy fog in eastern Egypt.
The collisions between 22 vehicles occurred near the Upper Egyptian city of Bani Suef, security officials said.
The injured were rushed to the hospitals while security forces cordoned the area.
In a separate incident, at least seven people were killed after a train collided with a vehicle in Al-Ayat area in Giza, officials said.
Egypt has one of the world's highest accident rates mainly due to careless driving, poor road and vehicle conditions which lead to many deaths and injuries to thousands of people every year.
The WHO ranks Egypt as the world's tenth worst country in road accidents, after India, China and the US.