The most attention-deserving spine deformity in childhood is scoliosis which means that it has to be diagnosed properly. The therapy varies from patient to patient according to the symptoms of the disease and it has to be revised from time to time. A full observational treatment consists of not only physical examination but also of applying imaging methods such as X-ray or CT. By using an ultrasound-based motion analysis system, the shape of the spine can be measured both at adults and children. Ultrasound-based spine measurement has a key role in diagnosing spine deformities in childhood and later, in the follow-up of rehabilitation. It has already been proved by previous studies that the CMS-HS ultrasound based motion analysis system and the measurement method used are suitable for measuring the degree of scoliosis. It also showed good correlation both at dorsal and lumbar sections with the degrees of frontal curvatures. In our research we took X-ray photographs of children suffering from scoliosis and compared kyphosis and lordosis values in the pictures with those we measured by the ultrasound-based motion analysis system. At 34 patients we calculated the degree of scoliosis in the X-ray images using the Cobb method and then the degree of kyphosis and of lumbar lordosis also by the Cobb method, and later we measured these parameters using the motion analysis system in a straight position. Comparing the results we found that there was a good correlation between the values. It can be stated that the CMS-HS ultrasound based motion analysis system and the measurement method were suitable to measure the changes of sagittal curvatures.