The objective of this study was to describe CT and MR findings in patients with allergic fungal sinusitis (AFS). CT and MR images were examined from 10 patients with histologically proven AFS. All patients demonstrated CT evidence of central sinus high attenuation and T2-weighted MR signal void corresponding to surgically proven areas of thick inspissated allergic mucin. AFS is a distinct clinical entity with a highly specific radiographic appearance based on CT and MRI.