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. Methods: Twenty-four patients with CRS were involved. SPECT findings for bone involvement and computed tomography-based staging (limited disease, stage 1; extensive disease, stages 2 and 3) were compared. These data were also analyzed in terms of subjective response to medical treatment and prognosis. Results: SPECT uptakes were positive in 79.2% (19/24) and negative in 20.8% (5/24) of the patients. SPECT was positive in 4/8 of the patients with limited disease and 15/16 of the patients with extensive disease. In subjective assessment of medical treatment 5/8 of the limited disease versus 1/16 the extensive disease patients had good response; whereas 5/ 5 of SPECT- patients versus 1/19 of SPECT+ patients had good response. Conclusion: Bone SPECT results were found to be correlated with the stage of CRS. Poorer subjective response was observed in patients with positive SPECT. Copyright © 2009, OceanSide Publications, Inc., U.S.A..