Objective: To evaluate whether serum glutamic acid decarboxylase (GAD), N-methyl-D-aspartate-receptor (NMDAR), and aquaporin-4 (AQP4) autoantibodies coexist in patients with neuromyelitis optica (NMO)/NMO spectrum disorders (NMOSD). Methods: Serum samples were collected from 98 patients with NMO/NMOSD. Serum GAD65, NMDAR and AQP4 antibodies were measured using a cell-based assay. Results: A total of 63 patients (64.3%) had myelitis and optic neuritis and satisfied the revised diagnostic criteria for NMO. Longitudinally extensive transverse myelitis was seen on spinal cord magnetic resonance imaging, showing continuous T2-weighted signal abnormalities in at least three vertebral segments in 26 patients (26.5%); 5 patients (5.1%) had recurrent optic neuritis, and 4 patients (4.1%) had brain syndromes with optic neuritis and myelitis. None of the 98 patients had diabetes, stiff-man syndrome, or epilepsy. All 98 patients tested positive for AQP4 antibody. No patients tested positive for GAD65 and NMDAR antibodies. Conclusions: In the present study, we found no simultaneous presence of serum GAD65, NMDAR and AQP4 antibodies in patients with NMO/NMOSD. © 2015 S. Karger AG, Basel.