The invention relates to a pipetting system, comprising a repeater pipette (1), a syringe (2) which is detachably connected to the repeater pipette, said repeater pipette (1) holding said syringe, and devices for pushing back the syringe piston (24) away from the syringe opening (28) and for pushing it forward to the syringe opening (24) in stages according to the volumes of liquid to be ejected by the syringe (2). Said devices have a working chamber (3) and a reserve chamber (4) which are filled with hydraulic fluid. A working piston (5) which is connected to the syringe piston (24), and an externally operated operating piston (7) are inserted into the working chamber (3) in such a way as to provide a seal. The reserve chamber (4) has a variable reserve volume and the working chamber (3) and reserve chamber (4) are connected by a valve device (12). When the working piston (5) is pushed into the working chamber (3) and especially when the syringe piston (24) is pushed back, this valve device (12) allows hydraulic fluid to pass from the working chamber (3) into the reserve chamber (4). When the operating piston (7) is pushed into the working chamber (3), the valve device separates the working chamber from the reserve chamber (4) so that the hydraulic fluid pushes the working piston out of the working chamber (3) in order to push the syringe piston (24) forward by one dosing stage, and when the operating piston (7) is pushed back out of the working chamber (3), the valve device allows hydraulic fluid to pass from the reserve chamber into the working chamber (3).