Orbital mucocele is one of the common orbital space-occupying lesions, which usually originate from the paranasal sinuses and invade the orbit; those that originate from the orbit are very rare. It can occur in all paranasal sinuses, with the frontal sinus being the most common, followed by the ethmoid sinus. Those that occur in the maxillary sinus, sphenoid sinus, and palatine bone bubble are rare. The frontal sinus is adjacent to the ethmoid sinus, with only a thin bone plate between them. If it occurs in either sinus, it is easy to invade the other sinus. When symptoms and signs appear, it has usually developed into a frontal-ethmoid sinus mucocele. Mucocele is a chronic inflammatory lesion, often complicated by bacterial infection, forming an acute suppurative inflammation, called a pyocele. Congenital mucocele can occur in the lacrimal sac area and is unrelated to sinus lesions. Clinically, mucocele is relatively common, mostly occurring in adults, and can occur in infants and children with a tendency to cystic fibrosis.