Because of the anatomic location and venous drainage pattern of the frontal sinus, complications commonly involve intracranial structures but can involve the orbit and adjacent bony and soft tissue structures also. Evaluation of patients by a thorough history and physical examination, culture of purulent discharge or infected bone, and axial and coronal CT scanning with contrast is important for diagnosis and treatment planning. Treatment of complications uniformly involves the use of intravenous antibiotics and appropriate drainage procedures to arrest the infection and allow for resolution of the inflammatory complication. Significant morbidity and mortality from complications can occur despite aggressive medical and surgical treatment.