Background: This retrospective study was conducted to describe and compare the clinical characteristics of primary mucoceles occurring in patients without a previous history of sinus surgery, the cause of mucoceles and secondary mucoceles resulting as a complication following endoscopic sinus surgery, and the Caldwell-Luc operation. Materials and Methods: This study reviewed 18 cases of primary mucoceles and 21 cases of secondary mucoceles, who were diagnosed and had received surgical intervention between 1995 and 2012. Results: The most common presenting symptoms in primary mucoceles were: Visual disturbance (18.6%), nasal obstruction (12.5%), and headache (12.5%). In secondary mucoceles, the most common symptoms were: Nasal obstruction (27.5%), rhinorrhea (15%), and postnasal drip (12.5%). The most common sites of origin for primary mucoceles were the ethmoid sinus (31.5%) and sphenoid sinus (31.5%). In secondary mucoceles, the maxillary sinus was the most common site of origin (40.7%), followed by the ethmoid sinus (29.6%). All patients with secondary mucoceles had a history of sinus surgery. Conclusions: Mucoceles are benign lesions of the paranasal sinus. Cases of secondary mucoceles that occur following sinus endoscopic surgery develop more frequently in the ethmoid sinus compared to those following the Caldwell-Luc procedure. Endoscopic intranasal surgery of mucoceles is a reliable therapeutic measure with a favorable long-term outcome.