A 72-year-old man from Tattershall is currently being treated in hospital after a crash on the A52 near Wrangle on Wednesday morning.
Two vehicles were involved in a collision which left one car in a ditch and the other on its roof.
Emergency services were called ot the location between Wrangle and Holland Lane End at 10.22 this morning.
A female passenger from one of the vehicles died at the scene.
A couple in their 60s, from Leicestershire, who were in the other vehicle are also being treated - none of their injuries are thought to be serious.
The road will remain closed for some time.
Any witnesses who have not already spoken with the police should call the Collision Witness Hotline on 01522 558855.