The collision happened on the A87 between Balmacara and Kyle of Lochalsh in the Highlands around 1pm on Sunday, August 22.
A Honda Jazz and a Skoda Rapid collided and Valerie MacKinnon, 73, from the Isle of Skye – a passenger in the Skoda – was seriously injured.
She died in Glasgow’s Queen Elizabeth University Hospital on Wednesday.
The 58-year-old male driver of the Honda and his 55-year-old female passenger were both released from hospital after treatment.
Sergeant Ewan Calder, of Highland and Islands road policing unit, said: “Our thoughts are with Mrs MacKinnon’s family at this time. Officers are continuing to carry out enquiries in relation to this collision and would appeal to anyone who has not yet spoken to officers to get in touch.”
People can call 101 quoting reference number 1969 of Sunday, August 22.