Background: Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are twoinflammatory disorders of the central nervous system with different pathogenesis. The aim of thisstudy is to evaluate endocrinopathy in these patients. Methods: By convenient sampling method, 20MS, 20 NMOSD and 20 normal age and sex matched as control were enrolled in this study. Hormonalassay including TSH, free T3, free T4, , FSH, prolactin, cortisol, IGFI, thyroid-stimulating hormone(TSH), free T3, free T4, luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin,cortisol, insulin-like growth factor I (IGF-I), urine specific gravity and anti-aquaporin immunoglobulinG (AQP4-IgG) level was measured. Also adrenocorticotropic hormone (ACTH) stimulation test wasdone for MS and NMOSD patients. Results: Hypothyroidism was prevalent and found in 30% of MS,40% of NMO patients, and only 9.5% of the controls. We detected greater rate of hypothyroidism inNMO patients compared to control (p=0.027). Mean level of anti-thyroglobulin antibody in MS andNMOSD patients was higher than control (p=0.037). One patient in MS group, 6 in NMOSD and 11control had IGFI level lower than lower limit of their age groups (p=0.001).Conclusions: Although the result of this study did not support significant hypothalamic-pituitary axisendocrinopathy in NMOSD compared to MS and controls, there is a higher prevalence of some hormonalabnormalities, especially thyroid dysfunction in NMOSD cases, that needs more clinicians’ attention.