The serious two-car accident happened just before 5pm on Sunday, May 3, at the junction of Flansham Lane and Hoe Lane, A259 just outside Bognor Regis.
The A259 remained closed for several hours before reopening at around 11pm.
A statement from Sussex Police said: “At 4.37pm on Sunday, May 3 2015, a red Nissan Qashqai travelling southbound on the A259 came into collision with a white VW van.
“As a result of the collision a local female aged 75 sadly died at the scene.
“The driver of the van, a local male aged 54, sustained serious injuries and has been flown to St George’s hospital in London.”
Anyone who witnessed the accident has been asked to contact Sussex Police on 101, quoting Operation Calcutta.