Evaluation of the therapeutic usefulness of the “pelvic C–clamp” (PCC) during emergency treatment of multiply injured patients with unstable disruption of the posterior pelvic ring. The data of 28 patients with polytrauma in combination with an unstable fracture of the posterior pelvic ring (average Injury Severity Score [ISS]: 49 points; average Polytrauma Score [PTS]: 41 points) were retrospectively analyzed from the moment they were admitted to the emergency room until 48 h after admittance. The PCC was used immediately for primary stabilization of the pelvis after clinical diagnosis of the unstable pelvic fracture. Main outcome measurements: development of mean blood pressure, development of oxygenation level, period of time until the PCC was placed, number of blood units needed, period of time until circulatory stabilization occurred. The PCC was applied in all cases within an average of 64.7 min after trauma. Seven patients (25%) died within the first 45 min after admission. The surviving patients showed: • an increase in mean blood pressure of 25% 20 min after application of the PCC, • a hemodynamic stabilization 6 h after application of the PCC, • a stabilization of the oxygenation level 6 h after application of the PCC, • a decrease in the number of required blood units 6 h after application of the PCC. The present study shows, that the application of the PCC to critically injured patients with unstable pelvic fractures leads to stabilization of the vital parameters within a short period of time.