A Capital Coast Health spokesperson said the woman remained in a critical condition in the hospital's intensive care unit.
District Command Centre Senior Sergeant Dan Foley said the woman had been thrown "some distance" in the collision, which also left the male rider of the motorcycle, a 27-year-old Otane man, with serious injuries. He was at Hawke's Bay Hospital in a serious but stable condition.
The female driver of the second vehicle, a stationwagon, who was in her 50s, was also taken to hospital but has since been discharged.
The crash saw the highway just south of Paki Paki closed for several hours while Serious Crash Unit officers worked at the scene.
Detours through Te Aute Rd and State Highway 50 were put in place.
Mr Foley said initial examinations at the scene indicated the vehicle might have been doing a U-turn at the time of the crash, and was in collision with the motorcycle which had been travelling south behind it.
This was the second serious crash near Paki Paki in less than a month.
Amberley Muller, 19, died on February 16 after her vehicle crossed into the path of an oncoming truck on SH2.
Her car became wedged under the truck, and fire crews spent a number of hours cutting her body from the wreckage after the three-vehicle crash.
This latest crash comes a month after a motorcyclist was killed in a collision involving a tourist driver on SH5.
