the attenuation values of the computed tomography were measured by a dual energy technique resulting in determination of the raw data of the region of interst. In our previous report CT values were correlated to the bone mineral concentration . Repositioning error was insignificant in our dual energy CT, We studied cortical mineral contents of L3 body in 120 healthy men and women. The results were as follows: 1. The bone mineral content on the mid-anterior portion of L3 vertebral body was highest in fifty decade of 304$pm$27mg/cc in men and 288$pm$22mh/cc in women. 2. The bone mineral content on the right postero-lateral portion of the L3 vertebral dody was highest value in fifth decade of 471$pm$31mg/cc in men and 412$pm$28mg/cc in women. On the left postero-lateral portion highest in fourth decade of 504$pm$40mg/cc in and 438$pm$42mg in women. 3. The mean values of the cortical bone mineral contents of L3 body were highest in fifth decade of 421$pm$30mg/cc in men and in fourth decade of 365$pm$34mg/cc in women