A 14-month-old girl was involved in a road traffic accident that resulted in an open book pelvic fracture and bilateral femoral fractures. Acute treatment involved a novel collar and the cuff pelvic closure technique to tamponade the pelvis and reduce bleeding. The patient was treated surgically with an external fixator, which provided good reduction of the pelvic and femoral fractures. A literature search found no previous information on open book pelvic fractures in infants younger than 2 years. The success of this surgery led us to suggest that the use of an external fixator is a potential treatment method for open book pelvic fractures and bilateral femoral fractures in extremely young infants.