Jayne Mansfield died in a tragic car accident on June 29, 1967, at the age of 34. She was traveling in a 1966 Buick Electra with her driver Ronald B. Harrison, her lawyer and boyfriend Samuel S. Brody, and three of her children. The car collided with the rear of a tractor-trailer on a dark Louisiana highway, likely obscured by a fog machine spraying mosquito fog, which contributed to the driver not seeing the truck in time

. The impact was severe, causing the car to slide under the trailer and shear off the top of the vehicle. Mansfield and the two men in the front seat were killed instantly, while her three children in the backseat survived with minor injuries

. Contrary to persistent rumors, Mansfield was not decapitated; the myth arose because her wig was thrown from the car and appeared in photos to resemble a severed head. Her death certificate states the cause of death as a crushed skull with avulsion of the cranium and brain, indicating severe head trauma but no decapitation

. Her death led to safety changes in trucking regulations, including recommendations for underride guards on tractor-trailers, sometimes called "Mansfield bars" in the U.S.