A new method of lower leg measurement for the determination of endochondral growth has been described quite different from the techniques commonly utilized. Endochondral growth of the lower leg can now be detected after one week (in provided case) the growth is at least 0.15 mm. The results of the lower leg measurement were compared with those of the ulnar length measurements in a four months lasting longitudinal growth study on twenty-one normal growing children. It appeared that the new lower leg length measuring technique with a margin of error in hundreds of millimeters is even more sensitive than the ulnar length measuring technique and a substantial improvement to conventional measuring methods in which the error fault is commonly expressed in millimeters. The new technique is especially suited for the assessment of short term growth in children whose ulnar length can not be measured accurately enough. Short term growth can now be followed in children from about the age of two years without using X-rays. This new technique permits: 1. Short term growth studies; 2. Studies of drug effects on tibia in single individuals within short time intervals; 3. Comparison of the growth in length of the lower leg and the ulna within time intervals as short as three weeks. 4. Studies in biorhythms of the lower leg length.