An antero-lateral cordotomy was performed on a 62-year-old man who had been suffering from intractable right chest pain caused by lung cancer. Six hours after the cordotomy a new pain occurred in an analogous part of the body on the opposite side; the intensity increased gradually and it became as severe as the original within 1 week. Reference of sensation from analgesic area of cordotomy to the opposite side of the body was induced by noxious stimuli. Intrathecal phenol block to the nerves conveying the cancer pain abolished the new pain and the reference of sensation from this blocked area, though it remained unchanged in other analgesic areas of cordotomy. This substantiates that the new pain was a reference of the original cancer pain.