Operation of a medical robotic device

A method for compensating for a deterioration in registration accuracy of a medical robotic device (2) relative to a body (1) to be operated on, the deterioration occurring during an operative and/or diagnostic intervention, and the medical robotic device (2) in this case has an end effector (3) for performing a diagnostic and/or therapeutic measure. The method includes selecting at least one landmark (B1, B2, C1, C2, D1, D2, E1 and E2) on an initial image data record of the body (1), registering the medical robotic device (2) relative to the body (1), positioning the end effector (3) in the vicinity of the landmark (B1, B2, C1, C2, D1, D2, E1 and E2), recording an intraoperative image data record in which the end effector (3) is captured with a region of the body (1) adjacent to the end effector (3), determining the position and/or the orientation of the end effector (3) in the intraoperative image data record, comparing this position and/or orientation with the landmark (B1, B2, C1, C2, D1, D2, E1 and E2) and identifying any divergence (d), and repositioning the end effector (3) in order to compensate for the divergence (d), in order thereby to achieve greater precision during the operative intervention.