Background: Myelin oligodendrocyte glycoprotein (MOG) has been a candidate target antigen in acquired demyelinating diseases of the CNS. The presence of MOG antibodies has been described in children with different demyelinating syndromes. Objective: to describe clinical spectrum of children seropositive for MOG IgG antibodies, clinically identified at a single centre in Buenos Aires. Methods: Between 2009 and 2012 serum and CSF samples collected from 105 consecutive children with an acute CNS inflammatory/demyelinating event were sent to Oxford for AQP4-IgG and MOG-IgG antibody testing, by immunofluorescence on live HEK cells transfected with either human M23-Aquaporin-4 or human MOG. Clinical and MRI features of MOG-IgG seropositive children were reviewed and their disease classified using 2013 consensus definitions. Results: Twenty-five patients (24%) were positive for MOG-IgG antibodies and negative for IgG-AQP4, 13 were boys (52%) and median age at onset was 7 years (1.75-16).  Longitudinal myelitis was identified in 19 (76%) children; thalamic involvement in 15 (60%); and tumefactive brainstem lesions in 13 (52%). Using the classification, nine children had NMOSD, nine had ADEM, four had optic neuritis, two a brainstem syndrome, and one an acute myelopathy. Ten (40%) children relapsed and seven of them were treated with azathioprine. Longitudinal analysis of available samples showed persisting MOG-IgG in 10/12 children. Conclusion: These results suggest that the presence of MOG antibodies may help define a subgroup of children with acquired demyelinating diseases. The heterogeneity of these children suggests that spectrum of an antibody mediated disease is not necessarily restricted to a single clinical phenotype.