The invention relates to a sun-protection roller blind for a vehicle window (4) having a curtain (1), which is attached to a curtain roller (2) such that the curtain can be unrolled and rolled up, and a holder (3) to which the curtain roller (2) is rotatably connected. Also provided is a flap (5) for the at least partial covering of an interspace between vehicle window (4) and curtain (1), wherein the closing of the flap is implemented by means of a cord (7). For this purpose, the cord (7) is fixed to a reference point (10) and to the curtain roller (2) and is connected to the flap (5) at at least one cord deflector (6, 9) of the flap (5). The cord (7) is unwound and wound up by the rotation of the curtain roller (2) and thus also moves the flap (5). In comparison with other driving possibilities (gear wheels, racks, carriages, connecting rods, levers, control cams), the cord (7) needs substantially less installation space. In addition, disturbing noises, such as flapping, can occur in the case of moving parts. In the case of a cord (7), this is virtually ruled out.