The size and configuration of the lumbar spinal canal constitute one of the important factors in the production of symptoms referable to cauda equina and nerve roots of the lumbar spine and the narrowness of the spinal canal. Numerous attempts have been made to measure the size of the lumbar spinal canal, but most of those are not sufficient to measure the oblique diameter of the lumbar spinal canal. Also, echographic diagnosis is much simple, safe, less expensive and non-invasive and furthermore demonstrates much more accuracy than other alternative and radiographic procedures. The purpose of this study is to establish the range of normal values of the oblique diameter of the lumbar spinal canal in Korean Army-aged group by echographic method in the interest of facilitating clinical evaluation of the lumbar spinal canal stenosis. The author measured oblique diamenter of the lumbar spinal canal in thirty healthy persons of both sexes of ages between nineteen and twenty-five years by ultrasound using sonolayergraphy model SSL-21A. Distance from the ligamentum flavum to the posterior longitudinal ligament was measured in millimeters with dial vernier caliper. Actual distance of oblique diameter of the lumbar spinal canal is obtained by multiplication of the distance of echogram by calibration factor 2.22. The results were as follows; 1. The mean values of the oblique diameter of the lumbar spinal canal in male and female between nineteen and twenty-five years of age were 14.77±0.85mm and 14.87±0.82mm in Ll, 13.99±0.87mm and 14.13±0.96mm in L2, 13.40±0.69mm and 13.71±0.75mm in L3, 12.88±0.69mm and 12.93±0.68mm in L4, 14.58±0.79mm and 14.42±0.84mm in L5 respectively. 2. The oblique diameter of the lumbar spinal canal was the widest at the first lumbar vertebra, the next at the fifth lumbar vertebra and the narrowest at the fourth lumbar vertebra. 3. There was no difference of diameter of the lumbar spinal canal between both sexes.