Fife Constabulary are investigating a road traffic crash near to Leuchars railway station which happened about 8.30pm on August 23.
A 13-year-old-boy was taken to Ninewells Hospital, Dundee, where his condition is described as critical.
The crash involved a white Hyundai car and happened on Station Road, Leuchars.
The road was closed for a few hours to allow an investigation to be completed.
Chief Inspector Adrian Annandale, Head of Road Policing, said: “We are investigating this incident and I would appeal to anyone who may have seen the collision, or anyone who was in the area at that time, to contact the Police on 0845 600 5702.”