Background: Chronic rhinosinusitis (CRS) is basically an inflammatory disease of the mucosa and periosteum of the sinuses. The possibility of local osteitis can cause persistent mucosal inflammation and lead to failure of treatment. Bone scintigraphy is the gold standard procedure for detecting the bone involvement. This study was designed to evaluate whether single-photon emission computerized tomography (SPECT) findings predict severity of chronic sinusitis and subjective response to medical treatment. A prospective case control study was done.