A man and a woman were flown by helicopter to an area trauma center when the motorcycle on which they were riding collided with a farm tractor around 4:25 p.m. Saturday on Route 19 near Grant City Road in Slippery Rock Township.
Their names and conditions were not available.
State police are investigating the accident.
Route 19 was shut down for over an hour during the investigation.
The Slippery Rock Township Fire Department and and Noga Ambulance were also on scene.