Abstract: A device for adjusting the circumferential register at rotary printing machines. At least one pulley engaging in a groove of a grooved cam is fastened to the gearwheel. Via tappets, the grooved cam is guided at the cylinder body so as to be axially displaceable. The groove is obliquely disposed as seen axially, and the grooved cam is axially movable via an adjusting means. A simple adjustment of the circumferential register is permitted, and such adjustment can be effected with great accuracy during machine operation. The drive forces caused by the gearwheel may be transmitted onto the cylinder body largely without play.