The emergency stabilization of unstable pelvic injuries, in particular, injuries to the posterior pelvic ring, can be achieved following reduction by application of the pelvic C-clamp. This and other procedures contribute to controlling what is almost always a life-threatening blood loss. The pelvic C-clamp is a temporary measure preceding definitive treatment of the injury. If this procedure is to have an optimal and lasting effect, the clamp must be applied correctly, provide adequate compression and stability, and be easy to handle. In one year, we applied the AO and ACE pelvic clamps in 9 clinical cases. Satisfactory primary compression and stability were achieved for unstable injuries with both clamps. It was more difficult to achieve good rotational stability as required for subsequent treatment with the ACE clamp due to its construction design.