Objective: To evaluate the direct costs of treating patients with neuromyelitis optica spectrum disorders (NMOSD) in outpatient care, from a hospital and Unified Health System (SUS) perspective. Methods: Observational study with data collection by microfunding, carried out with patients diagnosed with neuromyelitis optics, treated at a university hospital, in the city of Rio de Janeiro. Mann-Whitney tests were performed to measure cost differences between patient groups by disease severity and analysis perspective. Results: Nine individuals with a median age of 48 years (IQR 30 - 59 years) were included. The median total costs for patients with greater severity from the perspective of the SUS and the hospital were R$ 21,638.22 (IIQ: R$ 15,614.63; R$ 25,985.32) and R$ 32,094.11 (IIQ: R$ 25,610 .60; R$ 38,617.25) respectively. For patients with moderate severity the median was R$ 7,339.85 (IIQ: R$ 6,235.45; R$ 11,912.05) from the SUS perspective and R$ 11,505.80 (IIQ: R$ 7,339.85; R$ 22,424.76) from the perspective of the hospital, where the use of medications had a major impact. Conclusion: The main cost drivers were medicines, especially those used off-label, and procedures.