And Police Scotland officers are appealing for witnesses following the fatal crash, which happened on the B725 Dumfries-Glencaple road at around 12 noon on Monday.
The 86-year-old, male driver of a white Honda Jazz was taken to to Dumfries and Galloway Royal Infirmary, but later died.
The other car, a silver Vauxhall Corsa, was being driven by a 21-year-old female.
She was also taken to DGRI, and has serious injuries.
The crash happened about one mile outside Dumfries, and the road was closed for eight and a half hours to allow for investigations and was re-opened at 8.30 pm.
Sergeant Billy Broatch, of Dumfries and Galloway road policing unit, said: “Our thoughts are with the family and friends affected by this incident.
“We are carrying out extensive investigations into the incident and we would like to speak to anyone who witnessed the crash to establish the exact circumstances.
“In particular we would like to speak to anyone who may have dash-cam footage that could help with our enquiries to get in touch.”
Anyone who can help the investigation is asked to call Police Scotland on 101, quoting incident 1372 of 22 March.