We evaluated the clinico-pathophysiological features of three patients with acute autonomic and sensory neuropathy (AASN) who were followed for over 3 years. Signs of an autonomic disturbance including vomiting, anhidrosis, urinary disturbances, orthostatic hypotension and reduced coefficient of variation of the R-R interval on electrocardiography gradually improved about 1 year after onset. However, all three exhibited severe generalized sensory impairment for all modalities with the development of persistent sensory ataxia. No sensory nerve action potentials could be elicited and no somatosensory evoked potentials could be obtained. Sural nerve biopsy revealed severe axonopathy. In two patients, a high-intensity area was observed in the posterior column of the spinal cord on T2*-weighted axial magnetic resonance images. The level of neuron-specific enolase in cerebrospinal fluid was markedly elevated in two patients, indicating spinal nerve root or sensory neuron damage. Motor nerve function was well preserved in all patients. Our findings suggests that the major lesion in patients with AASN, particularly those with a sensory deficit, is present in the dorsal root ganglion neurons, that is there is a ganglioneuronopathy.