Police say it appears the man in his 40's stepped out into the path of a semi-trailer on the Pacific Highway around midnight.
He was taken to the John Hunter Hospital in a serious but stable condition.
Police are yet to speak to the man but it's suspected he may have been intoxicated when the incident took place.
Police say it could've been a lot worse if the truck driver had not been paying attention or had been travelling at the full speed limit.
