A car and a van collided on the A703, between Peebles and Eddleston, at around 4.40pm.
Police Scotland has confirmed that a 70-year-old woman from the local area sustained fatal injuries when the car she was travelling in collided with another vehicle, north of Redscarhead.
Her next of kin have been informed and have asked to be left alone to grieve in private.
Two other people, a man and a woman, sustained serious injuries and are currently receiving medical attention at the Royal Infirmary of Edinburgh.
Inquiries into the collision are ongoing and police are today appealing for any witnesses to contact them on 101 or the charity Crimestoppers anonymously on 0800 555 111.