AbstractAcute or subacute ataxia in young children is rare and, in most cases, the diagnosis of the underlying etiology can be challenging. An extensive number of possible causes must be considered when approaching a child with ataxia. We report the case of a 21-month-old girl with subacute-onset rapidly progressive ataxia, occurring few days after a gastrointestinal infection, without clear reduction of muscle strength in the limbs or other neurological signs. The development of a mild hyporeflexia of the lower limbs, thereafter, led to the suspicion of a Guillain–Barré syndrome (GBS) that was confirmed by appropriate investigations. This case confirms that a subacute afferent ataxia can be the main clinical symptom of GBS in young children, in whom this disease is rare and the diagnosis more challenging. Attention must be paid to the presence of other neurological signs that can lead to the diagnosis.