We evaluated 61 children with Guillain-Barré syndrome, 14 months to 14 years of age, admitted to the Hospital Nacional de Pediatría in Buenos Aires. According to the electrodiagnostic findings, they fit into two groups, those with acute motor axonal neuropathy (AMAN) (18 patients) and those with acute inflammatory demyelinating polyradiculoneuropathy (AIDP) (43 patients). Ninety percent of the children with AMAN resided in suburban or rural areas without running water, whereas half of the AIDP patients lived in a metropolitan district. Summer and winter months showed a higher incidence of both variants. Children with AMAN were younger, evolved more acutely, reached a higher maximum disability score, required assisted ventilation more often, had lower mean level of cerebrospinal fluid protein, improved more slowly, and had a poorer outcome 6 months and 12 months after onset. Electrophysiological findings in those with AIDP revealed a pattern of severe diffuse slowing in children 5 years old or younger and a multifocal pattern in children 6 years old or older. This difference was not reflected in the clinical picture. In contrast, AMAN showed a uniform pattern with normal sensory conduction, severely reduced compound muscle action potential amplitude, near normal conduction velocity, and early denervation. Epidemiological, clinical, electrodiagnostic, cerebrospinal fluid, and prognostic data indicate that these variants of Guillain-Barré syndrome should be regarded as different entities.