Identification of aquaporin-4 antibodies in neuromyelitis optica (NMO) is highly important to provide early diagnosis for starting pathogenetic treatment, and for differential diagnosis in neuromyelitis optica spectrum disorders (NMO-SD). In this paper, we review current pathogenetic and clinical aspects of NMO and NMO NMO-SD. We present our data on the identification of aquaporin-4 antibodies in CNS disorders. Aquaporin-4 antibodies were detected in 86.36% of patients with neuromyelitis optica, in 12.5% of patients with partial syndromes and in 100% of patients with systemic lupus erythematosus with longitudinally extensive transverse myelitis or optic neuritis. There was the correlation between the extent of lesion in the spinal cord and positive aquaporin-4 antibodies.