A device for robot-assisted surgery, comprising at least one non-sterile manipulator arm (12) having a coupling unit (100) with drive elements. The device further has an instrument unit (300) which comprises a surgical instrument (500) and a sterile sterile unit (400) for coupling the surgical instrument (500) to the drive elements of the coupling unit (100). The coupling unit (100) comprises a translatory drive element (110, 112) for generating a translatory drive movement and a rotatory drive element (114, 116) for generating a rotatory drive movement. The sterile unit (400) has a translationally driven element (408, 410) couplable to the translatory drive element (110, 112) and a rotationally driven element (412, 414) couplable to the rotatory drive element (114, 116). The device has a sterile lock (200) which is capable of being coupled to the coupling unit (100) and to the sterile unit (400).