Paranasal sinus fungus ball is an extramucosal mycosis, usually occurring in immunocompetent people as a monolateral lesion. To review the literature data and to report the Policlinico S. Matteo, University of Pavia experience, 81 patients presenting paranasal fungus ball have been treated (January 1994 to May 2005). Twenty-seven men and 54 women (19-91 years old; mean 49.4 years) were considered. Seventy-three patients had a single sinus affected, but eight presented multiple localisations. Maxillary was the most involved sinus followed by sphenoidal and ethmoidal. Moulds have been isolated in 28/81 cases. Histology showed fungal colonisation but not invasion in all cases. Tomography showed bone erosion in 33.3% of patients. All have been treated only by functional endoscopic sinus surgery. Seventy-seven of 81 patients have been cured. Four of 81 patients needed another surgical treatment. Follow up was between 6 and 132 months (average: 63 months). Fungus ball is a sinusal pathology caused by mycetes like Aspergillus spp. Histology confirms the fungal aethiology excluding tissue invasion. Mycological culture consented to identify the pathogenic mould in 34.5% of cases. Actually functional endoscopic sinus surgery is the gold standard for treatment of this pathology, and antifungal therapy is unnecessary.