We describe a 32-year-old female who presented with a painless, moderately hard mass in the left inferior medial canthal region which had been present for about 6 years. She suffered from epiphora in the left eye in that time. The nasolacrimal system was completely patent on irrigation. Computed tomography showed a nodular mass with a diameter measuring about 25 mm located over the upper portion of the left lacrimal sac. The lesion was found to be a cyst located separately with close proximity to the lacrimal sac via anterior orbitotomy. Histopathologic examination revealed a cystic cavity lined by columnar to cuboidal epithelium consistent with a cyst derived from lacrimal sac epithelium. The patient has remained free of symptoms with a patent lacrimal system during the follow-up period of 1 year, without recurrence of the lesion. Orbital cysts of lacrimal sac derivation should be considered in the diagnosis of medial orbital tumors. Careful evaluation clinically with imaging studies and planning surgery constituted adequate therapy in this case.