We have presented an interesting case of an unexpected orbital tumor in a 5-month-old female healthy baby who presented initially with a 1-week history of acute left proptosis, swollen eyelid, conjunctival chemosis and exposure keratopathy. She was treated with intravenous antibiotics without any improvement and was referred for the drainage of the left orbital abscess. The procedure was performed with partial resolution, however the proptosis persisted and an underlying orbital pathologic lesion was suspected. Further exploring the left orbital revealed a partially cystic tumor. The histopathologic features were consistent with a mature teratoma. The case is presented with a brief discussion on this entity to attract the attention of general ophthalmologists to such tumors in the orbit.