Fungal rhinosinusitis occurs in different forms depending on race and region. While allergic fungal rhinosinusitis is common in Caucasians, fungal ball (FB) is more common in Asians. However, most cases are reported as unilateral, and clinical data on bilateral FB (BFB) are rare. Therefore, the purpose of this study was to analyze and to compare the clinical characteristics of BFB and unilateral FB (UFB) in Koreans.