Roll over protection device for vehicles

The anti-roll protection has a roll bar (1) set in a guide unit fixed on the vehicle and in the normal state held against spring force by a holder in a lower retracted rest position. The bar head (5) connecting the two arms (3,4) of the roll bar has in addition to the support face formed by a shaped body connecting the arms also a further support face which is formed by an integral projection (5b 5c) on the shaped body of the bar head connecting the arms. The bar head is preferably made of a fibre-reinforced plastics.