Abstract: A method for providing patient registration without fiducials comprises the steps of: spatially placing an ultrasound image of a patient randomly at different starting positions relative to a preoperative image; creating an independent registration corresponding to each different starting positions, by optimizing a spatial transformation between the preoperative image and the ultrasound image to provide a first batch of registrations; executing a second registration to fine-tune the alignment between the preoperative image and the ultrasound image; and concatenating the spatial transformation to obtain spatial transformation between the patient in an operating room and a corresponding preoperative image.