The fatal victim, an 18-year-old male, was pronounced dead at the scene of the accident on the westbound A303 at about 21:00 BST on Friday.
The second victim, a 23-year-old man from Liss, was taken to Southampton General Hospital.
The driver of the Fiat motorhome was uninjured. Police are appealing for witnesses.
One pedestrian died and a second suffered life-threatening injuries in a crash involving a motorhome in Andover.