Two women have been seriously injured in separate car crashes, requiring them to be airlifted to Waikato Hospital.

The first woman, a 24-year-old, suffered a serious spinal injury after the car she was in ran off the road into a ditch at 6pm on Monday.

The Rotorua-based BayTrust Rescue Helicopter was dispatched to assist the Taupo-based Greenlea Rescue Helicopter at the scene of the accident at the turnoff from Poihipi Road and Whangamata Road.

On Waitangi Day, a 68-year-old Wellington woman sustained various head, limb, and abdominal injuries after her car left the road and impacted a bank in Mapiu, south of Te Kuiti.

The Waikato Westpac Rescue Helicopter responded to the accident just after 12pm, landing at the Mapiu School grounds where the woman had been transported by an ambulance.

She was stablised by the on-board Intensive Care Paramedic before being airlifted to Waikato Hospital for further assessment and treatment.