A 46-year-old white man complained of swelling in the left orbital region. The only significant event in his medical history was minor trauma which occurred during ice hockey 15 years previously. On admission, the only clinical finding was left-sided exophthalmos. Computed tomography and magnetic resonance imaging revealed a left intraorbital cystic mass lesion. The cystic mass was completely removed through a left subfrontal extradural approach. There was no anatomical contact with the paranasal sinuses and the orbital walls were intact. The cystic mass was isolated in the orbital cavity. Histological examination confirmed the diagnosis of mucocele. Generally, the cause of mucocele is chronic sinusitis, but we suspect that the old minor trauma was the most likely cause in the present case.