Klippel-Trenaunay syndrome (KTS) is a rare congenital malformation of unknown etiology characterized by cutaneous hemangiomas, venous varicosities and bony and soft tissues hypertrophy usually affecting one limb. Several complex anomalies involving various organs and systems have been described, whereas involvement of the peripheral nervous system has rarely been reported in KTS. We describe the case of a 67-year-old woman with KTS and peripheral neuropathy related to the presence of epineurial microscopic arteriovenous anastomoses (AVA) and endoneurial vascular coils in sural nerve biopsy from both hypertrophic and non-hypertrophic limb. The maintenance of AVA has been proposed to be the cause of the hypertrophy. The observation in our patient of AVA in non-hypertrophic limb contrasts with this hypothesis.