35 cases of frontal sinus mucoceles treated from 1977 to 1991 are reported. The average of age was 41 years with 74% of men. The clinical presentation was a frontal or fronto-orbital pyocele in 40% of the cases, with palpebral fistula in 11 cases; one patient had visual loss. Unilateral exophtalmos was the initial complaint among five patients (14%). Surgical treatment, surrounded by massive antibiotherapy, required always curettage and aeration of the sinus by desobstruction of the nasofrontal duct and insertion of a tube in the duct to the nasal cavity. Exenteration was mandatory in one patient. Failure was due to recurrence in 3 cases. The gravity of paranasal sinuses mucoceles prescribe a correct evaluation of their usual predisposing factors.