Presentations of the cases and interventions: Spontaneous cerebrospinal fluid leakage was diagnosed in two patients with chronic renal failure. Anterior fossa repair was pedormed in the first case because of the enlarged foramina of the lamina cribrosa on cranial computed tomography. Sphenoid sinus was obliterated through the transsphenoidal route because of the suspected cerebrospinal fluid collection inside the sphenoid sinus in the second case. No cerebrospinal fluid leakage was found on postoperative one year follow up in both cases.

Conclusion: We concluded the renal osteodystrophy associated to the chronic renal fai!ure caused to skull base erosion and spontaneous rhinorrhea in the patients. Anahtar Kelimeler : Chronic renal failure, spontaneous rhinorrhea