Background: There are multiple etiologies of heterotopic ossification (HO) and limited information regarding the outcome of HO complicating specific injuries in children. The aim of this study was to examine the characteristics and long-term results of treatment of HO in pediatric patients with severe traumatic brain injury (TBI). Hypothesis: Our global null hypothesis was that there would be no difference in the rate and severity of HO in children with TBI, in comparison with adults. Patients and methods: The files of all patients treated at a pediatric rehabilitation center with severe TBI during the study period were retrospectively examined. Patients diagnosed with HO during the rehabilitation period were examined in the clinic. Results: Of 78 patients with TBI, HO was diagnosed in six patients at an average of four months after the injury. No difference was found between patients with or without HO, regarding age, gender, GCS, length of stay in rehabilitation facility or ventilation during this period. In all the six patients diagnosed with HO, the involved side was the spastic and paretic limb, 4 in the elbow, 1 knee and 1 hip joint. Symptoms resolved in five patients with non-steroidal anti-inflammatory drug (NSAID) treatment. One patient required surgical excision of the elbow HO, due to a progressive ulnar neuropathy. Discussion: Severe TBI in children may be complicated by HO of the spastic and paretic limb at a rate of 8%, the majority in the elbow joint. The rate and manifestations of the HO are less severe than in adults. Although treatment and timing of excision of HO is controversial, a peripheral neuropathy may be an indication for early excision of the HO mass.