Abstract: Localized herpes zoster (HZ) is rarely associated with a concomitant syndrome of inappropriate antidiuretic hormone secretion (SIADH). We present the case of 59-year-old woman being treated for chronic lymphocytic leukemia who had 2 separate episodes of localized HZ complicated by simultaneous SIADH. No other identifiable cause of SIADH was identified. Hyponatremia improved with antiviral therapy, and resolution paralleled improvement in skin lesions in both instances. This represents a unique situation of documented recurrence of SIADH with relapsed HZ. Clinicians should consider the possibility of concomitant SIADH in a patient with localized HZ even in the absence of symptoms. We suggest that the severity of HZ manifestations and the degree of hyponatremia may be positively correlated. Further investigation into the pathophysiologic mechanism for this association is warranted.