The incident occurred on the A711 Dalbeattie Road near to Tower Wood at 9.52 on Sunday, and involved a black-coloured Vauxhall Astra.
A statement from Police Scotland said: “Sadly, both occupants of the vehicle died at the scene.”
The road was closed to allow for collision investigation and re-opened at about 4.47 am today.
PC Rebecca Wylie of the Road Policing Unit said: “We are carrying out a full crash investigation into this collision and would ask that anyone who may have witnessed it to get in touch with us at Dumfries on the 101 number.
“We are particularly keen to speak with the occupants of an estate car that we believed may have stopped at the scene shortly after the crash.”