Conclusive evidence for involvement of the peripheral nervous system in decompression illness is lacking. We report a case of decompression illness associated with shoulder pain and the clinical features of median nerve injury at the wrist. Initial recompression and hyperbaric oxygen treatment produced prompt relief of all symptoms and signs, but carpal tunnel syndrome subsequently recurred. Nerve conduction studies confirmed median nerve conduction delay at the wrist. Repeat measurements after treatment with hyperbaric oxygen showed electrophysiologic improvement that was consistent with improvement in symptoms. We believe this is the first objectively substantiated case of injury to the peripheral nervous system caused by decompression illness.