Dysesthesia, allodynia, distal muscle weakness, and sensory impairment were noted in two patients with acute thallium intoxication. Two months later, nerve conduction studies showed an axonal degeneration. Sural nerve biopsy disclosed a decreased fiber density in the large myelinated fibers. Quantitative sensory testing also revealed an impairment of pinprick, temperature, and touch sensations. Cutaneous nerve biopsy confirmed a loss of epidermal nerves indicating an involvement of the small sensory nerves.