The diverse etiologies of cerebrospinal fluid leaks and encephaloceles make it essential to have a thorough understanding of the underlying pathophysiology, principles of treatment, and treatment options to achieve an excellent outcome. Our current diagnostic studies and preoperative imaging for localization of skull base defects permit accurate identification with minimal operative morbidity. The site of the skull base defect ultimately determines the specific surgical approach. Almost all skull base defects in the anterior skull base are amenable to endoscopic repair. However, external approaches are still mandatory for posterior table defects in the frontal sinus located beyond the reach of frontal sinus instruments. Reconstruction of the skull base defect is dependent on the etiology of the leak and other factors, including the underlying intracranial pressure. This article will highlight the surgical techniques and perioperative care relevant to sinonasal cerebrospinal fluid leaks and encephaloceles. © 2006 Elsevier Inc. All rights reserved.