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Sponsorships or competing interests that may be relevant to content are dis-closed at the end of this article. Objective. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been reported as a paraneoplastic syn-drome in many different types of malignancies. Several case reports of SIADH have been reported in patients with olfac-tory neuroblastoma (ONB), but the exact incidence is unknown. The purpose of this study was to review our experi-ence with olfactory neuroblastoma and to identify all patients who had a history of SIADH prior to the diagnosis of ONB. Study Design. Case series and chart review Setting. Tertiary care university-affiliated medical center. Subjects and Methods. A total of 21 patients presented to our institution with ONB between 1997 and 2009. All records were reviewed for a history of preoperative hypo-natremia or SIADH. Results. Three patients were identified who had a history of SIADH prior to the diagnosis of ONB. Immunohistochemical staining of the tumor specimens from the 3 patients with SIADH was positive for arginine vasopressin. SIADH resolved in all 3 patients after successful treatment of ONB. Conclusion. Although uncommon, SIADH can be the present-ing symptom of ONB and should be considered during the workup for idiopathic SIADH. Keywords olfactory neuroblastoma, syndrome of inappropriate anti-diuretic hormon