Cerebrospinal fluid leak (CSF leak) is typically classified into spontaneous/idiopathic, traumatic, and iatrogenic. The most common cause of cerebrospinal fluid leak is a craniofacial trauma, making up 80% of CSF leaks in some reviews. During endoscopic sinus surgery, the most common site of injury is the cribriform plate/fovea ethmoidalis (80%) followed by the frontal and sphenoid sinuses. During neurosurgical procedures, the sphenoid sinus is the most common site of injury; this is related to the advances and frequency of transnasal endoscopic approaches to pituitary tumors. Following history taking and clinical examination, if a CSF leak is suspected, confirmation with beta-2 transferrin and/or beta-trace protein is essential. Site identification can be aided by HRCT, MRI, and CT cisternogram. Intraoperative identification of the CSF leak site can be achieved by intrathecal fluorescein or topical fluorescein application. Treatment varies depending on the cause, site, and size of defect.