An adjustable arm-rest for vehicles has a fixed part and a movable part, hinged so as to move between a lowered angular position and a raised angular position; and a system for adjusting the inclination of said movable part between the lowered position and the raised position. The adjusting system has a freewheeling bearing which allows the movable part to rotate only from the lowered position to the raised position, and releasing means which enable the movable part to move from the raised position to the lowered position.