A system for precision guidance of surgical procedures on a patient is suggested, comprising: a three-dimensional digital representation of the pre-procedural geometry of a relevant part (2) of the patient (10), a three-dimensional digital representation of the intended post-procedural geometry of the relevant part of the patient including any implant (1) or other structures intended to be attached to the patient, a movable electrooptical camera (3) mounted in a known position and orientation relative to a surgeon (4) such as a head mount, a first carrier (5) comprising at least 3 targets (6) to be observed by the camera, said carrier to be mounted in a known position and orientation relative to the relevant part of the patient, a second carrier (7) comprising at least 3 targets to be observed by the camera, said carrier to be mounted in a known position and orientation relative to an implant or surgical instrument, a computer (8) for calculating the relative positions of the first and second carriers with at least 3 targets, and of the camera, based on observations from the camera, software, residing on the computer, calculating the relevant projection of a digital representation (11) of the patient to a display in order for the displayed projection to match with the surgeons current physical view of the patient.
