Abstract: The invention provides a method of treating chronic rhinosinusitis such as allergic fungal sinusitis comprising daily oral administration of a composition from more than 500 mg to about 800 mg, preferably about 625 mg or 725 mg terbinafine base equivalent as hydrochloride, or a molar equivalent in other acid addition salt or free base form, for a duration effective to reduce the symptoms of, or eliminate chronic rhinosinusitis; it further concerns the use of terbinafine in the manufacture of a corresponding medicament, and packs containing a plurality of corresponding compositions and medicaments.