Police are appealing for witnesses and information after a collision on the A21 between Sedlescombe and Whatlington.
It happened shortly before 2pm on Monday, October 7, and involved a silver Skoda Citigo and a grey Jeep Compass, just north of the junction with Marley Lane.
The driver of the Skoda, a 62-year-old man from St Leonards, sustained serious injuries.
He was airlifted to the Royal Sussex County Hospital in Brighton where he remains in a stable condition in intensive care.
The driver of the Jeep, a 59-year-old woman from Kent, sustained minor and was taken to the Conquest Hospital in Hastings.
Officers are investigating, and witnesses or anyone with relevant information such as CCTV or dashcam footage of the vehicles in the area at the time is asked to come forward.
Information can be reported to Sussex Police online, quoting serial 585 of 07/10.
