In a retrospective study authors refer to the treatment results in four patients with mucocele of the paranasal sinuses, whowerehospitalized during a 30-months period at the Department of Otorhinolaryngology of the Charles University Hospital, in Prague, Czech Republic. In all patients the frontal sinus was involved, in three cases the involvement was unilateral, in one case bilateral. In the medical history of all patients, an injury, inflammation, or surgery of the paranasal sinus in the past (5 - 30 years ago) were present. In three patients, proptosis of the eye, swollen upper eyelid, and diplopia were discovered firstly by ocular examination. All patients underwent external approach surgical treatment, in four cases it was the frontoethmoidectomy sec. Jansen-Ritter, in one case the osteoplastic frontal craniotomy was performed. The postoperative follow-up period is 2 - 30 months.

        Key words: mucocele, complications, frontoethmoidectomy, osteoplastic frontal craniotomy