Abstract : Lymphocytic hypophysitis, a rare autoimmune disorder causing inflammation of the pituitary gland, often presents diagnostic challenges due to its varied manifestations and rarity. This report discusses a unique case of a 20-year-old female patient presented with polyuria, polydipsia, and fatigue. The initial laboratory evaluation suggested diabetes insipidus (DI), and magnetic resonance imaging (MRI) revealed an enlarged pituitary gland with mild, uniform thickening of the pituitary stalk. The patient was diagnosed with lymphocytic hypophysitis and managed with desmopressin and hydrocortisone. This case report highlights the challenges in diagnosing and treating lymphocytic hypophysitis presenting with central DI. The report emphasizes the importance of considering lymphocytic hypophysitis as a potential differential diagnosis in cases of unexplained DI, particularly in young women. Additionally, it underlines the significance of a comprehensive diagnostic approach, including laboratory tests and imaging studies, to reach a conclusive diagnosis in such rare and complex cases. The management of lymphocytic hypophysitis involves addressing the underlying autoimmune inflammation and associated hormonal imbalances. In this case, the use of desmopressin and hydrocortisone proved successful in managing the patient's symptoms and improving her overall clinical condition.