Fungal infection of the nose and sinuses is an uncommon condition which is now being increasingly recognized. In this study we review clinicopathologic features in a series of 26 cases encountered at King Faisal Specialist Hospital and Research Centre over a five-year period. The cases were divided into four categories according to the following histopathologic features: allergic fungal sinusitis (11 cases), aspergilloma (one case), chronic indolent fungal sinusitis (five cases), and acute fulminant fungal sinusitis (nine cases). In the cases of allergic fungal sinusitis and aspergilloma, the fungal hyphae were limited to the sinus activity without any evidence of invasion. Invasion in the wall of the sinus, as well as the surrounding tissue, was noted in cases of chronic indolent fungal sinusitis and acute fulminant fungal sinusitis. All patients were treated surgically and those cases with evidence of tissue invasion on pathologic or radiologic examination were given antifungal therapy. The prognosis was excellent in the cases of allergic fungal sinusitis and aspergilloma. Most of the patients with acute fulminant fungal sinusitis died of uncontrolled fungus growth. In the cases of chronic indolent fungal sinusitis, all patients are still alive, but two patients had loss of vision due to fungal invasion. Fungal sinusitis with absence of tissue invasion is easily treated by surgery alone. However, in cases with tissue invasion, a combination of surgery with antifungal therapy may be successful. Acute fulminant fungal sinusitis, however, has a grave prognosis.