Air traffic at Kenya's Jomo Kenyatta International Airport was temporarily suspended after a dead boy was found on the runway, police say.
It is unclear whether the bruised body was that of a stowaway or a street boy, airport CID chief Joseph Ngisa said.
The airport was shut for about 40 minutes as police removed the body, the airport authority said.
In November, the body of a stowaway was found after a plane landed at the airport, local media report.
The BBC's Caroline Karobia in Nairobi says the nationality of the boy, believed to be between the age of 12 and 15 years, is not yet known.
Police are trying to establish whether he fell from a plane, or was a street boy who had breached security by getting on to the runaway and then died, she says.
The temporary suspension of flights only affected the operations of one airline.