Within the past few years an unusual group of tumors of the spinal cord, not heretofore recognized as a definite clinical entity, has come under observation. They are discrete, sharply circumscribed, ventral, extradural chondromas lying in the midline or slightly to one side of the midline, usually in the region of the fourth, fifth or sixth cervical vertebrae. The more typical of these tumors present sufficiently defined clinical signs to permit recognition before operation. The most characteristic picture is that of marked unilateral spasticity, with atrophy and weakness of the muscles of one or two cervical segments at the level of the tumor and on the side of the spasticity, and changes in pain and temperature sense on the opposite side. Muscle, joint, vibratory and discriminative sensations are unaltered. The upper limit of the sensory changes is usually several segments lower than the atrophy and motor weakness, which, as has