A 28-year-old female with Klippel-Trenaunay-Weber syndrome associated with an arteriovenous malformation (AVM) of the spinal cord is reported. She was admitted to our hospital with a 4-month history of steadily progressive weakness and dysesthesia of the legs. A nevus flammeus, varices, hypertrophy and elongation of the left leg had been present since her infancy. These symptoms progressed and she became unable to walk and pass water by herself. Myelography disclosed a spinal AVM extending from Th11 to L2. Angiography confirmed the presence of stretched and tortuous vessels as well as an arteriovenous shunt in the left leg. Magnetic resonance imaging showed a high-intensity area extending from Th10 to L2. Following laminectomy from Th10 to L2 and resection of the AVM, her motor and bladder functions worsened. However, 6 months later, her motor function improved to the preoperative state and the bladder dysfunction disappeared. The coexistence of Klippel-Trenaunay-Weber syndrome with spinal AVM, considered to be rare, is discussed, and the pertinent literature is reviewed. The case presented here is the first to have been surgically treated in Japan.