BACKGROUND: Epidemiological studies of neuromyelitis optica spectrum disorder (NMOSD) show variability due to differences in methodologies, diagnostic criteria, and geographic factors. OBJECTIVE: This study aimed to determine NMOSD's epidemiological profile in Türkiye using official health records covering over 95 % of the population. METHODS: Data were collected using ICD-10 codes (G36.0) from the Health Record Reporting System (HRRS). Patients with at least three G36.0 codes or one G36.0 code combined with a prescription for rituximab, eculizumab, or tocilizumab were included. Nationwide prevalence of NMOSD in 2022 and incidence (2018-2022) were calculated using census data. RESULTS: We identified 1,623 patients meeting inclusion criteria. The prevalence was 1.9 per 100,000, and the incidence in 2022 was 2.1 per 1,000,000. A decreasing prevalence gradient from east to west was observed. The mean (±SD) patient age was 44.2 ± 15.7 years. Among 193 aquaporin-4 antibody positive patients, the female-to-male ratio was 8.2. Additionally, 83 % received at least one disease-modifying treatment. CONCLUSION: NMOSD epidemiological features in Türkiye align with European data but remain lower than figures reported in African and Asian populations. Further research is needed to enhance the understanding of NMOSD in this population.