Uric acid (UA) has been reported to be reduced in the serum of patients with multiple sclerosis (MS) and optic neuritis (ON). However, the relationship between UA and neuromyelitis optica (NMO) was unknown. NMO was claimed to be a distinct nosologic entity from MS. The aim of our study was to investigate the correlation between serum UA level and the clinical characteristics of NMO. The serum UA level was measured in 403 Chinese patients; 69 with NMO, 32 ON, 127 MS, 80 cerebral infarction (CI) patients, and 95 healthy controls (CTL). Serum UA level in NMO was significantly lower than that in CI (249.89 +/- 93.74 vs. 315.42 +/- 85.57 micromol/L, p = 0.004) and CTL (249.89 +/- 93.74 vs. 314.33 +/- 102.05 micromol/L, p < 0.0001). However, no difference was found between NMO and MS (p = 0.496) or NMO and ON (p = 0.858). When the analysis was performed in the female cohort separately, UA level was significantly lower in females than in males in all groups. It was also shown in our study that UA level in patients with NMO was not correlated with disease activity revealed by MRI, disease disability or duration of disease. Our results indicated a reduced serum UA level in patients with NMO.