Egyptian state TV says a midday bomb blast in downtown Cairo killed one person and wounded four others.
The explosion took place in a crowded area near the High Court. Police have cordoned off the area and explosives experts are searching for other devices.
Egypt has seen a series of attacks mainly targeting security forces since the military ousted Islamist President Mohammed Morsi in the summer of 2013. Outside of the restive Sinai Peninsula, most attacks have involved small, homemade explosives and have caused few casualties.
The attacks have raised fears ahead of an economic conference later this month aimed at attracting foreign investment.
On Sunday a bomb went off near a police station in the southern city of Aswan, killing two civilians and wounding a soldier and four others.