Police Scotland are investigating a two vehicle collision that occurred on the B994 Kintore to Kemnay road near Upper Cottown at the weekend.
The collision happened at around 5.40pm on Saturday, October 20, and involved a black Seat Leon motor car and a black Honda motor scooter.
The 19-year-old rider of the scooter was taken to Aberdeen Royal Infirmary where he remains in a serious condition.
The occupants of the motor car sustained minor injuries.
Sergeant Peter Henderson of the Road Policing Department said: "Our thoughts at this time are with those involved and their families.
"An investigation into the collision is underway and we have already spoken to a number of witnesses. In order to help establish the cause of the collision I would urge anyone who saw either vehicle prior to the collision or the collision itself and who has not already come forward to get in touch.
"Likewise if any motorists believe they may have dash-cam footage which could assist our enquiries I appeal to them to come forward.
"Anyone with information can contact Police on 101 or Crimestoppers on 0800555111 in confidence, quoting incident number PS-20181020-3000."