The crash happened on the A72 Peebles to Innerleithen road on Saturday morning.
Three men aged 87, 71 and 42 were taken to hospital after the crash, involving a red Vauxhall Meriva and a silver Honda CR-V.
Police said the 87-year-old man died a short time later.
Sergeant Neil Inglis has appealed for witnesses to the accident, near the entrance to the village of Cardrona at around 11.10am.
He said: “We are keen to speak to anyone who witnessed the collision, or who stopped to assist and have yet to come forward.”
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