A thread-forming screw has a shank which, in a front region of the shank, has a tip for insertion into a bore in a substrate, and in a rear region of the shank, has a drive for transmitting a torque to the shank. The shank has a spiral-shaped groove and a thread spiral which is inserted into the spiral-shaped groove. The spiral-shaped groove has a front flank and a rear flank disposed opposite the front flank. The front flank, at least regionally, has a different part flank angle than the rear flank.