Diagnostic criteria for allergic fungal sinusitis have not been established, and clinical information consists primarily of isolated case reports. We proposed five diagnostic criteria for allergic fungal sinusitis including: (1) the demonstration of the characteristic eosinophil-rich allergic mucin visually or histopathologically, (2) a positive fungal stain or culture from the sinus at surgery, and (3) the absence of immunodeficiency or diabetes. With these criteria, seven patients in our metropolitan area with allergic fungal sinusitis were identified in a short period. Initial symptoms in our seven patients reflected those in 99 case reports in that two children were first seen with proptosis, one child and three adults with nasal congestion, and one adult with symptoms of chronic sinusitis. All had pansinusitis as shown on x-ray films. Six patients were atopic, five had nasal polyposis, and five had Curvularia species cultured from the sinuses. Infections with Bipolaris species, asthma, and chronic sinusitis were less common in our patients than in those previously reported. Recurrent symptoms and additional surgery sometimes resulted when the diagnosis was delayed by failure to obtain silver stains for fungus on surgical material sent for histopathologic review. Sinus tomography showed that the fungal material in the sinuses was of high density, which distinguished it from polyps or bacterial exudate. Bony compression, erosion, and rupture of the sinus walls were common. Results of IgE levels, precipitin determinations, and eosinophil counts were variable in both our patients and those in the literature. On the basis of our review, we believe that the simple diagnostic criteria proposed are appropriate for both research and clinical purposes.