East Midlands Ambulance Service were called to Shireoaks Road, in Rhodesia at 4.17pm this afternoon.
A spokesman said that a man was taken by paramedics to Bassetlaw Hospital.
Police were also called to the scene.
A spokesperson for Nottinghamshire Police said: "We were called by East Midlands Ambulance Service after a man was found not breathing, slumped over inside somebody’s car.
"There have been no collisions. At the minute, it looks like a medical episode.”