A 25-year-old man [120 kg, 180 cm (body mass index=37 kg x m(-2)] underwent laminectomy and discectomy under general anesthesia in the prone position. Hall frame was used for supporting his body. In spite of a small amount of bleeding, the patient showed metabolic acidosis and hypotension with limb cyanosis one hour after changing position. Ephedrine hydrochloride was effective for the treatment of his hypotension. However, limb cyanosis continued until turning him to the supine position. Anuria continued during prone position. We consider that Hall frame allows patient's abdomen to hang freely, but compresses the body more strongly than expected, especially with heavy patients. It is possible for morbidly obese patients to develop seriously inhibited circulation due to Hall frame. Prone position with careful selection of support system may prevent these complications.