A new skin contraction (10 cm segment) method for measuring segmental and "total" spinal movement in the sagittal plane is described and compared with the modified Schober test, finger-floor distance and goniometry. Three consecutive 10 cm segments are marked out along the spine from the lumbosacral junction with the patient in full flexion. The amount of contraction occurring within each segment is measured after maximal spinal extension. Skin contraction correlated significantly with comparable measurements by other methods. Interobserver variation was not significant. Mean patient measurement time (+/- SD) was 124 +/- 59 seconds. The 10 cm segment method was found to be more sensitive than other available clinical techniques for detecting loss of spinal mobility in ankylosing spondylitis.