BACKGROUND: Between 29% and 67% of neuromyelitis optica spectrum disorder patients have cognitive alterations. OBJECTIVE: To assess the frequency of cognitive impairment in patients with neuromyelitis optica spectrum disorder in Mexico using the Brief International Cognitive Assessment for Multiple Sclerosis. METHODS: We evaluated 40 neuromyelitis optica spectrum disorder patients and 40 healthy controls from Mexico. RESULTS: 28 (70.0%) patients with neuromyelitis optica spectrum disorder had cognitive impairment in two or more cognitive domains. Student´s T test showed statistically poor performance by neuromyelitis optica spectrum disorder patients compared to healthy controls on all three neuropsychological test scores. This significant difference was observed on the Symbols Digit Modalities Test (t = 8.875; p ≤ 0.001); California Verbal Learning Test-II memory (t = 10.418; p ≤ 0.001); and Brief Visuospatial Memory Test Revised (t = 6.123; p ≤ 0.001). CONCLUSIONS: This study showed that 70% of neuromyelitis optica spectrum disorder patients exhibited cognitive impairment in two or more cognitive domains. Determining the frequency of cognitive impairment will guide the decision of Neuropsychologists in planning cognitive rehabilitation across various domains.