['Neuromyelitis optica spectrum disorders (NMOSDs) and multiple sclerosis (MS) are distinct clinical entities but are poorly distinguished by serum markers, including serum anti-aquaporin-4 (AQP4-Ab). We examined if testing for serum anti-nuclear antibodies (ANAs) and AQP4-Ab improved diagnostic sensitivity for NMOSDs.', 'Chinese patients with NMOSDs (n = 74) or MS (n = 49) were screened for serum ANAs (all patients) and AQP4-Ab (58/74 NMOSDs and 45/49 MS patients). The NMOSDs group included patients with neuromyelitis optica (NMO; n = 53), recurrent longitudinally extensive transverse myelitis (rLETM; n = 20), and recurrent optic neuritis (n = 1).', 'The seroprevalence rate for ANAs was significantly higher in the NMOSDs group than the MS group (45.9 vs. 2%; p < 0.01). Similarly, AQP4-Ab seroprevalence was higher in NMOSDs than MS (56.9 vs. 4.4%; p < 0.01). Sensitivities and specificities for diagnosing NMOSDs were 51.7 and 97.8% using ANAs, 56.9 and 95.6% using AQP4-Ab, and 74.1 and 93.3% using both assays.'] Does combined screening for serum anti-nuclear and anti-aquaporin-4 antibodies improve diagnostic accuracy for distinguishing neuromyelitis optica from multiple sclerosis?