A 67-year-old lady died in a crash on the A15 Eastern Bypass in Lincoln, according to police.
She was driving a car when it collided with another vehicle between Wragby Road and Greetwell Road around 16:45 BST yesterday (Monday).
Lincolnshire Police said the woman was brought to hospital and ultimately died.
Her family has been notified, and they will be assisted by specially trained officers, the force stated.
The driver of the second vehicle was gravely hurt.
Investigators are looking for witnesses and any dashcam footage.