The invention relates to a thread-forming screw having a shank (10) which, in a front region of the shank, has a tip (11) for insertion into a bore in a substrate, in a rear region of the shank, has adrive for transmitting a torque to the shank, and has a spiral-shaped groove (20), and having a thread spiral (30) which is inserted into the spiral-shaped groove, wherein the spiral-shaped groove has a front flank (21) and a rear flank (22) situated opposite the front flank. According to the invention, it is provided that the front flank at least regionally has a different part flank angle thanthe rear flank.