Police and ambulance crews - including the air ambulance - were called to Welland Road in the city at about 3.40pm yesterday.
A spokesman for the East of England Ambulance Service said: “We were called at 3.38pm yesterday with reports of a cardiac arrest in Welland Road, Dogsthorpe.
“We sent two ambulances, an ambulance officer, community first responder and Magpas Air Ambulance.
“One person was taken to Peterborough City Hospital by air ambulance for further care.”
There is no further information available on the man’s condition.
A police spokesman said they were called to assist with crowd control and road closures.