During operative fracture treatment the surgeon depends on fluoroscopic or X-ray radiological images as well as CT scans or MRI scans. This means that the surgeon sees only images at a given moment. Continuous imaging is technically complex and is accompanied by considerable exposure to radiation. Between images the surgeon has to depend on his or her knowledge of anatomical relationships and three-dimensional orientation. This may lead to the incorrect positioning of implants with ensuing morbidity and sometimes even death. Throughout the surgical procedure, computer assisted surgery (CAS) informs the surgeon of the exact position of the instruments in relation to the affected bone. The concept can be compared to that of the global positioning system (GPS) that is used by motorists. Clinical applications of CAS have been described for the operative treatment of vertebral fractures as well as fractures of the pelvis, hip and long bones. In reconstructive surgery, CAS is used for positioning the patient for total hip and knee surgery. The potential advantages of CAS are: increased accuracy, safety and reproducibility combined with lower radiation levels. Currently CAS is not widely used. There are a number of reasons for this. The technique is expensive and complex although the newer systems are more user friendly. It is possible that in the future CAS will be in standard use in orthopaedic and trauma surgery.