PURPOSE: To evaluate the outcomes of surgical treatment modality in unstable sacral fractures combined with spinal and pelvic ring injury depending on the presence of spino-pelvic dissociations. MATERIALS AND METHODS: The subjects were 16 patients, with unstable sacral fractures combined with spinal and pelvic ring injuries, were operated from July 2004 to January 2011. The patients were divided into 2 groups depending on the presence of spino-pelvic dissociations: those with dissociations were group 1, and those without dissociations were group 2. Group 1 was treated with spino-pelvic fixations using iliac screw, while group 2 was treated with percutaneous iliosacral screw fixations. The availability of the radiological bony union with its application periods, and clinical results using visual analogue scale (VAS) and oswestry disability index (ODI) were evaluated, retrospectively. RESULTS: Out of 16 patients, 8 patients in group 1 were treated with spino-pelvic fixation using iliac screw, and 8 patients in group 2 were treated with percutaneous iliosacral screw fixation. The mean bony union period was 17.4 weeks in group 1, and 19.6 weeks in group 2. The Mean VAS and ODI scores on the last follow-up were 2.5 points and 15.6 points in group 1, 2 points and 18.8 points in group 2, respectively. Both groups had favorable clinical results at the last follow-up. CONCLUSION: For surgical treatments of unstable sacral fractures, spino-pelvic fixation using iliac screws is advised for cases with combined spino-pelvic dissociation, while percutaneous iliosacral screw fixation is advised for cases without combined dissociation.