Allergic Aspergillus sinusitis was first reported in 1983. We present the first three cases of allergic fungal sinusitis caused by the black fungus Bipolaris spicifera. The patients were young, atopic, and immunocompetent. All three patients demonstrated pansinusitis with nasal polyps and underwent multiple surgical procedures. Pathologic features included a characteristic mucoid exudate containing eosinophils, Charcot-Leyden crystals, and fungal hyphae. In two cases there was bony erosion revealed by computed tomography scan but no histologic evidence of direct fungal invasion into the mucosa or bony trabeculae. Immunologic features, including total eosinophil count, total serum IgE, immediate and late-phase skin response to B. spicifera, serum precipitins, and specific IgE and IgG to B. spicifera, are described. B. spicifera is a previously unrecognized cause of allergic fungal sinusitis that may be an underdiagnosed disorder. This diagnosis should be considered in atopic patients with nasal polyps and pansinusitis unresponsive to conventional medical therapy. Diagnostic criteria include characteristic histologic allergic mucin, culture identification of fungus, positive immediate cutaneous reactivity to fungal extract, positive serum precipitins, and elevated specific IgE and IgG antibodies.