Objective: Unicameral bone cyst is a nonneoplastic bone lesion characterized by its tenacity and risk of recurrence. Pathological fracture is common and is often the presenting symptom. The objective of the present study was to evaluate the results of hybrid external fixator for the treatment of a unicameral bone cyst with a pathological fracture. Methods: Hybrid external fixator for the treatment of a unicameral bone cyst was performed in twelve patients. These patients presented with a pathological fracture and were managed immediately with hybrid external fixator, of whom four had been managed conservatively at other clinics before they were referred to our department. The cyst was located in the proximal humerus in all patients. The mean age of the patients at the time of surgery was 8.7 years, and the mean duration of follow-up was 32.6 months. Radiographic evaluation was performed according to the criteria of Capanna et al., and the cyst was classified as completely healed, healed with residual radiolucency (osteolysis), recurred, or having no response. Results: The healing period ranged from three to eight months. Eight cysts healed completely, and three healed with residual radiolucent areas visible on radiographs. There was recurrence of one cyst that had healed with residual radiolucency. All of the cysts in the present study responded to treatment. A modulation of hybrid external fixator was necessary in three patients, as the bars had become too short after bone growth or the pins had been loose. No major complications were observed. Conclusion: Hybrid external fixator provides early stability, which allows early mobilization and thus obviates the need for a plaster cast. This method of treatment also allows for an early return to normal activity.