Inappropriate secretion of antidiuretic hormone (ADH) secondary to vincristine therapy has been reported frequently. But there has been five previous reports of vinblastine associated SIADH in the world and in 4 reports, bleomycin and cis-platinum were used along with vinblastine together. Because penetration of vinka alkaloids into CSF of humans is known to be poor, it has been suggested that lowering the osmotic threshold for vasopressin release induces SIADH in humans. In our case, the patient did not receive cis-platinum during chemotherapy. From this we concluded that vinblastine alone can induce SIADH without nephrotoxicity of cis-platinum. We experienced a case of inappropriate ADH secretion secondary to vinblastine therapy in a 5- month-old male infant who has been taking vinblastine due to Langerhans cell histiocytosis. We report this case with a brief review of related literatures.