A white Ford Transit van, a silver-coloured Peugeot 206 and a white Renault Master van were involved in the collision on the A701 road at the turn-off for Ae Village in Dumfries and Galloway.
The 49-year-old woman driver of the Peugeot was removed from her vehicle by firefighters and then flown by Helimed to the Queen Elizabeth University Hospital in Glasgow with serious injuries.
The 50-year-old man driving the Ford Transit was taken to Dumfries and Galloway Royal Infirmary as a precaution, while the driver of the other van was not injured.
Police are appealing for information about the crash, which happened at around 4pm on Monday October 29.
Constable Paul Watson, of the Roads Policing Unit, said: “The road at the scene was closed until the early hours of Tuesday 30 October in order to carry out a full collision investigation and to clear the vehicles from the road.
“We are appealing for anyone who may have witnessed this collision to call us at Dumfries using the 101 number, and quoting the reference number 2658 of 29/10