Incidence of fungal sinusitis due to the genus Fusarium has increased during the last two decades. We report a case of fungus ball sinusitis with multiple sinuses involvement in an Iranian 21-year-old woman. The patient was diagnosed as having a fungus ball-type sinusitis in computed tomography scan. The sinus biopsy revealed fungal structures on histopathological and direct microscopic examinations and a Fusarium species arose in culture. Partial sequencing of the translation elongation factor 1-alpha identified the isolate as F. proliferatum. Removal of all lesions by endoscopic surgery resulted in a favorable outcome. To the best of our knowledge, this is the first case of F. proliferatum-associated fungus ball which involved multi-sinus and highlights the efficiency of molecular methods for discrimination of fungal agents involved.