Operative management of pelvic ring disruptions remains a challenge for the orthopedist. Surgical stabilization of an unstable pelvic ring not only involves urgent control of shock, but also protects soft tissues and enables the patient to ambulate earlier and to be comfortable when resting. Appropriate management of pelvic ring injuries requires understanding the anatomy and biomechanics of the pelvis and the mechanism of injury. The choice of posterior stabilization depends on the type of fracture. In this study we evaluated posterior tansiliac fixation using threaded compression rods (sacral bars), 1 of the techniques for treating pelvic instability with disruption of the posterior osseous - ligamentous complex. We used this method during 1987 - 1991 on 17 multitrauma patients with unstable pelvic injuries. We also conducted a long-term follow-up of more than 2 years. The 2 type C3 patients required revision of the posterior fixation, due to loss of stability and recurrence of dislocation of the sacroiliac joint. This seems to support the view that posterior sacral bar fixation is not suitable for bilateral rotational and vertical instability, and that it should be limited to certain posterior injury patterns, including lateral compression injuries and unilateral vertical instability when the contralateral hemipelvis is stable. It is important therefore, that the trauma surgeon be familiar with more than 1 technique of stabilization. Our study indicated that fixation with sacral bars is still an easy, safe and useful method for treating posterior pelvic instability, even though anatomical reduction of the sacroiliac joint is difficult. It should be one of the techniques with which the orthopedic trauma surgeon is acquainted and is ready to use when necessary.