Osteomas of the paranasal sinuses rarely lead to intracranial manifestations. We present an unusual case of a giant frontal sinus osteoma leading to subdural empyema formation. Determine the origin and the optimal surgical approach of these unusual lesions by analyzing giant osteomas of the frontal and ethmoidal sinuses in the literature. We report a rare case of giant frontoethmoidal osteoma with intracranial extension in a 34-year-old man, revealed by seizures. Neuroradiological studies revealed frontoparietal subdural empyema associated to a large osteoma in the right frontal sinus. The patient underwent surgical evacuation of the empyema and resection of the osteoma in one stage operation of decompressive craniotomy. The patient recovered very well after surgery and postoperative antibiotic therapy. This case represents in the literature only the third-reported case of subdural empyema complicating frontoethmoidal osteoma. The surgical treatment options, including open surgery techniques and endoscopic approaches, as well as pathogenesis are discussed according to the relevant literature.