Three patients developed acute pure sensory ataxic neuropathy. Two of the three patients had a recent Campylobacter jejuni infection. Patient 1 had monospecific IgG anti-GD1b. Patients 2 and 3 had cross-reactive IgG anti-GQ1b and anti-GD1b and patient 2 also had IgG anti-GT1a. Motor nerve conduction studies were completely normal. Sensory conductions showed reduced amplitude or absent sensory nerve action potentials with normal or slightly slowed conduction velocities. In patient 2, serial electrophysiological studies showed reappearance and improvement of sensory nerve potential amplitudes in 4 weeks. All patients recovered completely in 2 months and sensory potential amplitudes normalized in 3-5 months. Our findings: (1) confirm the existence of a pure acute sensory ataxic neuropathy with cross-reactive IgG anti-GQ1b and anti-GD1b as a variant of Guillain-Barré syndrome; (2) expand the clinical presentation of Guillain-Barré syndrome after C. jejuni infection and suggest that molecular mimicry is at the basis of acute sensory ataxic neuropathy; and (3) indicate that, in acute sensory ataxic neuropathy with prompt recovery, the site of the lesion is not in the primary sensory neurons and the pathophysiological mechanism may be functional in nature.