Cerebrospinal rhinorrhea occurs when there is a fistula between the anterior skull base and the nasal cavity, tympanic cavity and sinuses. It commonly occurs following head trauma or as a result of incranial surgery. Cerebrospinal fluid leakage is a rare condition that can lead to the development of serious consequences, such as meningitis. This article reviews the laboratory diagnostic of cerebrospinal rhinorrhea, including the detection of glucose and chloride in nasal discharge. This was the traditional method used to diagnose CSF leak, but has a poor positive predictive value. The article also describes the use of prostaglandin D synthase, commonly known as beta trace protein and beta 2 transferrin to detect CSF leak.