A bumper beam for a vehicle has a hat shaped profile with the crown (12-14) facing the vehicle and has a cover (17) that gives the bumper beam a closed profile. The bumper beam has two mountings (20, 21) that usually are adapted to be fitted to the side rails of the vehicle. The cover is extended on both sides past the mountings, but leaves the outer portions of the hat beam open. The crown of the open portions of the hat beam have a longitudinal indentation (32) and a profile height that decreases towards the ends.