The use of cutaneous markers as an accurate method of measuring spine motion was studied in five cadaveric spine samples and two live subjects. The markers were placed on the skin over the spinous processes, a particularly suitable site in thin subjects for determining the displacement of the underlying skeletal segments because the deep layer of the skin is in adherence with their fibrous surrounding sheath. Fairly close correlations were obtained in the sagittal and frontal planes between the two sets of measurements. However in the transversal plane the technique is unreliable because of tightening of the skin.