Background: Neuromyelitis optica spectrum disorders (NMOSD) are a group of antibody-mediated chronic inflammatory diseases of the central nervous system. Rituximab is a monoclonal antibody that leads to a reduction in disease activity. Objective: To evaluate the efficacy of rituximab as monotherapy in NMOSD and to determine whether the efficacy varies depending on the presence of antibodies in this cohort. Method: This multicentre national retrospective study included patients with NMOSD treated with rituximab at least for 12 months from Turkey. The primary outcomes were the change in the annualised relapse rate, the Expanded Disability Status Scale (EDSS), the number of relapse and radiological activity-free patients. Results: A total of 85 patients with NMOSD were included in the study. Of 85 patients, 58 (68.2%) were seropositive for anti-Aquaporin4-IgG (antI-AQP4-IgG). All patients were Anti-Myelin Oligodendrocyte Glycoprotein IgG (anti-MOG-IgG) negative. The median follow-up for rituximab treatment was 21 months (Q1 16-Q3 34.5). During rituximab treatment, the mean annualised relapse rate (ARR) significantly decreased from 1.45 ± 1.53 to 0.15 ± 0.34 (P <.001). In subgroup analyses, the mean ARR decreased from 1.61 ± 1.65 to 0.20 ± 0.39 in the seropositive group and 1.10 ± 1.19 to 0.05 ± 0.13 in the seronegative group. The mean EDSS improved from 3.98 ± 2.04 (prior to treatment onset) to 2.71 ± 1.59 (at follow-up) (P <.001). In the seropositive group, mean EDSS decreased from 3.94 ± 1.98 to 2.67 ± 1.54, and in the seronegative group, mean EDSS decreased from 4.07 ± 2.21 to 2.79 ± 1.73. There was no significant difference between anti-AQP4-IgG (+) and (-) groups in terms of ARR and EDSS. Sixty-four patients (75.2%) were relapse-free after the initiation of treatment. Seventy patients (82.3%) were radiological activity-free in the optic nerve, area postrema and brainstem. Additionally, 78 patients (91.7%) showed no spinal cord involvement after the treatment. Conclusion: Rituximab therapy is efficacious in the treatment of Turkish NMOSD patients independent of the presence of the anti-AQP4-IgG antibody.