The invention relates to a medical image registration method in which an actual patient's body or portion of a patient's body (22) is positionally registered to a patient image created using a medical body-imaging technique such as MR, CT or x-ray imaging, wherein in a medical navigation system, the actual spatial position of at least a part of the body or body portion (22) is assigned to a respective position in the image of said body or body portion (22), wherein the part of the body or body portion (22) comprises a registration area in the form of the surface of a substantially rigid body structure, in particular an inner structure, made of bone or cartilage. The invention also relates to a medical image registration device which comprises a surface scanner (15) for scanning a registration area comprising the surface of a substantially rigid body structure, in particular an inner structure, made of bone or cartilage.