Pelvic ring injuries due to high energy forces are among the most serious, involving the musculoskeletal system. Life threatening hemorrhage, local and distant associated injuries, deformity, pain and diminished functional capacity are all potential problems for a patient with a disrupted pelvis. There is a clear correlation between total blood loss, incidence of associated injuries, final functional result and the type of pelvic ring injury. Between January 1987 and July 1989, 44 patients with an unstable lesion, type B or type C in Tile's classification have been treated in the University Hospital Gasthuisberg of the Katholieke Universiteit Leuven. In 28 cases, primary stabilisation was done by means of an external fixator, "Monofixateur" type. The overall mortality rate was less than 7%. Thirty-five patients could be seen for follow-up six months to three years after injury. Our findings confirm that compared to type B lesions there is a higher incidence of pain, permanent deformity and diminished functional capacity in type C lesion (p < 0.05). The external fixator, used in the immediate post injury period provides an effective splint that reduces bleedings from bone and veins but cannot maintain reduction in lesions with rotational and vertical instability. In these cases, a semi-elective internal fixation, after defining the exact patho-anatomy by means of a CT-scan has to be performed in selected areas.