A method and a device for fixing and synchronizing rotary pistons in a rotary piston pump involves introducing the rotary pistons into the pump space of the rotary piston pump. A shaft stub of each rotary piston is then pushed through a pump rear wall onto a driveshaft provided for the respective rotary piston. The rotary pistons are aligned and synchronized in the pump space via a template, the template being fixed detachably to a pump housing. The shaft stubs of the respective rotary piston are connected, after the synchronization, in each case via a clamping device in a friction-locked manner to the respective driveshaft, outside the pump space.