This paper reports a new real-time ultrasound method for measuring vertebral rotation to detect lateral spinal curves of adolescent idiopathic scoliosis (AIS) in 50 adolescents referred consecutively to hospital from the scoliosis school screening service in Nottingham, England (girls 39, boys 11, median age 15 years). Radiographically the curve types were thoracic 21, thoracolumbar 14 and lumbar 15 with a mean Cobb angle of 17° (range 2-40°). Ultrasound laminal rotation was measured in the prone position from Tl-Sl by one of three observers. The ability of ultrasound laminal rotation to predict the scoliosis curve (Cobb) angle was compared with surface back shape angles calculated at 18 levels from angles of trunk inclinations (ATIs) measured by a Scoliometer in the standing forward bending position. The findings show that ultrasound laminal rotation (and Scoliometer ATI) each with a threshold of 8° predicted Cobb angles of 20° or more with a sensitivity of 95% (79%), specificity of 68% (35%) and positive predictive value of 64% (43%). Overall, the ultrasound method is significantly better than the Scoliometer method for discriminating curves with Cobb angles of 20° (p=0.003, McNemar test). The findings suggest that in school screening for scoliosis ultrasound laminal rotation measured in the community may reduce the number of false positives who are referred to hospital and x-rayed.