Inflammatory pseudotumors are rare and are characterized by solitary, demarcated lesions with numerous inflammatory cells, mesenchymal cells, and collagenous fibers. They usually occur in the lung, but have also been reported in the thyroid gland, pleura, liver, kidney, bile duct, spinal cord, testis, and soft tissues. Since inflammatory pseudotumors of the head and neck are very rare, their clinical and radiological features, prognosis, and therapeutic management have never been clearly described. We report a case of inflammatory pserdotumor arising in the ethmoid sinus and the clinical, radiological, and histopathological findings.