The precise measurement of leg length and leg length discrepancies (LLD) plays an important role in the examination of lumbar spine and lower extremities. Those real LLD which may be posttraumatic or idiopathic, can sometimes hardly be differentiated from LLD caused by spinal scoliosis or malposition. Although there is no final agreement, to which extent a LLD becomes clinically significant, most authors state that clinical assessment of LLD by tape measure or lengthening of the short leg with blocks of known thickness is highly unreliable. Radiological methods are necessary for precise detection of LLD less than 10 mm. Since previously reported non-invasive, ultrasound-supported leg-length measurement methods proved to be complicated and unhandy, a new method was developed. To avoid radiation exposure accuracy and precision were tested on human cadavers and were compared to clinical assessments by tape measurement. A measurement device was constructed consisting of a wire rope meter and a length millimeter digital display. Measurements were taken with the examined person in supine position. The device was placed beyond their feet and the end of the rope was hinged with a metal brace to a convenient transducer in exact middle position. Thus the middle of the ultrasound monitor concords with the end of the rope. The medial knee joint and ventral hip joint were used as standardised sonographic landmarks. Ten not pre-selected mortants were measured in this manner and additionally clinical LLD was obtained with a tape measure (medial ankle to anterior superior iliac spine). Afterwards all distances were anatomically prepared and measured with a meter stick.(ABSTRACT TRUNCATED AT 250 WORDS)