: Between 1968 and 1984, III patients were treated for unstable fractures of the pelvic ring. Cause, incidence, accompanying local lesions, mortality, Injury Severity Score (ISS) and mode of treatment were retrospectively analysed. ISS and mortality were closely correlated. The overall mortality was 19% and the average ISS 53. The mortality of the conservatively treated patients was 21.8%, for the operative group the mortality was 8.3%, while the ISS was the same in both groups. From these results we conclude that unstable pelvic fractures, which are almost invariably associated with other serious injuries, should be treated aggressively by external and/or internal fixation.