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Backgroud: LGI1(leucine-richanti-glioma1protein) is one of the latest identified voltage-gated potassium channels related antigens. Anti-LGI1 encephalitis affected the limbic systems presenting with subacute onset of progressive neurological, cognitive, psychiatric disturbance and life threatening obstinate hyponatremia. However, Anti-LGI1 encephalitis was mostly considered to be non-malignancy related. The hyponatremia mechanism remains to be elusive. Case presentation:Here we firstly report a 71-year-old female diagnosed of anti-LGI1 encephalitis after renal clear cell carcinoma resection. The old female discovered a renal mass which was identified as renal clear cell carcinoma. Two months after the renal carcinoma resection, the patient fell down frequently and showed discontinuous neuro-psychiatric disorders manifested as memory decline, disorientation, and unintentional upper limb movements as typical faciobrachial dystonic seizure episode. She also had hyponatremia. The combination of her clinical presentations and laboratory assessments supported a diagnosis ofanti-LGI1 encephalitis and renal salt wasting. The Immunohistochemistry studies of the kidney resection indicated circulating LGI1 antibodies in sera might be binding to extracellular LGI1 predominantly in the proximal tubule where the major defect in solute transport exists in renal salt wasting. Conclusion: Anti-LGI1 encephalities with renal carcinoma indicated its paralimbic pathology origin. The early diagnosis and immune-modulation therapy could lead to good outcome. The hyponatremia in anti-LGI1 encephalitis was renal salt wasting instead of syndrome of inappropriate secretion of antidiuretic hormone.