Spontaneous cerebrospinal fluid fistula secondary to clival defect is a very rare condition. Only 2 cases are reported previously in the literature. We report a case of clival defect in a young male patient presenting with spontaneous cerebrospinal fluid rhinorrhea which failed detection by conventional CT and MRI. The patient was referred to our center after failed anterior cranial fossa repair. Thorough radiological investigations successfully detected the defect in the posterior wall of the sphenoid sinus 5 mm distal to the posterior limit of the floor of the sella just on the midline. The fistula was managed successfully through an endonasal transsphenoidal approach. We present the case reviewing the literature concerning the pathophysiology of spontaneous cerebrospinal fluid fistula through the sphenoid sinus.