Objective Due to the high prevalence of syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). This study was carried out to evaluate the prevalence and relevant parameters of SIADH in children with septic and aseptic memingitis hospitalized at Kashan Shahid Beheshti Hospital between 1996 and 2006. Materials & Methods This descriptive study was conducted on 230 patients with meningitis hospitalized in the pediatric wards of Kashan Shahid Beheshti Hospital between 1996 and 2006. Relevant information (age, gender, type of meningitis, serum sodium and potassium, urine specific gravity (USG), blood sugar, blood urea nitrogen, serum creatinin, hydration condition) was collected from patients' records. Datawas analyzed using Mann-Whitney and K2 tests. Results Out of 230 patients with meningitis, 33 had incomplete records and only 197 patients were recruited for this study. Sixty eight cases (34.5) suffered from SIADH. It was more frequent among 1-2 year old children. According to this research, SIADH was diagnosed in 57 of the 121 patients with hyponatremia, 58.7 of the 167 patients with USG > 1.004, 74 of the 93 patients with serum osmolity < 280 mOs/L and 100 of the patients with BUN < 10 mg. Conclusion Due to the high prevalence of SIADH in septic and aseptic meningitis and its complication, it is recommended to restrict fluid therapy and monitor serum sodium, urine specific gravity and other diagnostic tests for SIADH
