A clinicopathological study is presented of 5 patients with a pseudosyringomyelic dissociation of sensory loss and severe autonomic disturbances related to diabetic polyneuropathy. Sensory loss which followed a pattern that suggested a length-related degeneration of fibres was associated with spontaneous pains in 3 patients. Plantar ulcers and neurogenic arthropathies were also present in 3 patients. The pathological changes in sural nerve biopsies included a severe loss of unmyelinated and small myelinated axons which appeared to be involved earlier than larger myelinated fibres. Distal degeneration of single fibres with subsequent axonal sprouting from the proximal axon was demonstrated in all patients. This severe axonal neuropathy was associated with primary and secondary segmental demyelination. Our observations are consistent with a progressive centripetal degeneration of axons in predominantly sensory diabetic polyneuropathy.