Hundreds of people were attending the late party on Friday on the Princess Hidy ferry when it began sinking in the river off Beni Sweif, a town some 201 kilometres south of Cairo, officials said.
The boat tilted and sank as people were singing and dancing, police said, speaking on condition of anonymity because they were not authorised to speak to the media.
Many of the passengers were rescued but dozens weren't immediately accounted for, police said.
There were no reports of any confirmed deaths.
Police said at least six people were hospitalised with injuries, but the nature of the injuries was not immediately available.
Rescuers told police that the scene was chaotic and many on board had jumped into the water.
Nile boats are usually used for weddings and other celebrations in Egypt, especially in summer. - DDNEWS
