BACKGROUND Flexible nailing has become the preferred implant for pediatric patients with tibial shaft fractures that require operative fixation. Immediate definitive fracture fixation with flexible nails in patients with high-energy, open fractures has not been examined. The purpose of our study was to determine if immediate flexible nailing of open pediatric tibial shaft fractures is safe and efficacious from a bone healing, wound, and infectious standpoint. METHODS A retrospective review of 26 tibial shaft fractures consecutively treated with flexible nailing at our institution from 2003 to 2010 was performed. Age, mechanism of injury, associated injuries, presence of compartment syndrome, antibiotic administration, systemic insults, time to union, as well as bone healing (nonunion, delayed union, malunion, leg length discrepancy, growth arrest), wound, and infectious complications were collected. Comparisons were made between patients with open fractures and those with closed fractures. RESULTS We identified 14 patients with open fractures and a control group of 12 patients with closed injuries who underwent flexible nailing. Patients with open fractures were more likely to have polytraumatic injuries (71.0% vs. 25.0%, P = 0.04). There was no difference (P = 1.0) in the rates of compartment syndrome (open = 14.0%, closed = 17.0%) between the 2 groups. Systemic complications (pulmonary compromise and increased intracranial pressure) were noted in 2 patients who underwent immediate nailing of their open fractures; both of whom had closed head injuries. There was no difference (P = 1.0) in the rates of wound/infectious complications between the open (7.0%) and closed (4.0%) fractures groups, with no cases of wound breakdown or osteomyelitis. There was an increased rate (P = 0.02) of bone healing complications in the open fracture group (21.0% vs. 4.0%); all in patients with Gustilo type 2 or 3 injuries. All patients achieved radiographic union at final follow-up. CONCLUSIONS Immediate flexible nailing of open pediatric tibial shaft fractures can be safely performed with minimal risk of wound or infectious complications. Clinicians should understand that prolonged bone healing (particularly in Gustilo type 2 or 3 injuries) should be expected in patients who undergo immediate flexible nailing of their open fractures. Open tibial shaft fractures are high-energy injuries, and should be seen as surrogate markers of polytrauma in the pediatric population. The risk of compartment syndrome is high regardless of whether a patient has a closed or open tibia fracture, and caution should be used in performing flexible nailing in patients who may have closed head injury due to a risk of systemic complications. METHODS Level III, therapeutic study, retrospective cohort.