Abstract: A roller blind comprising a horizontal roller for supporting the blind and mounted for rotation about its own axis, a blind having an upper edge fixed to the roller and a free lower edge, resilient means tending to bias the roller towards a position in which the blind is rolled up, and a centrifugal-mass brake for slowing the rotation of the roller during rolling up of the blind. The centrifugal-mass brake is carried by a fixed support structure outside the roller and the rotor of the brake is connected to the roller through the interposition of step-up wheels and a one-way clutch device adapted to break the connection between the rotor of the brake and the roller when the blind is lowered, the one-way clutch device and the step-up wheels also being carried by the fixed support structure, outside the roller.