The holding power of four different bone screws was measured by a pull-out test in 40 cadaver hips from 10 females and 10 males over 70 years of age. Each femoral head was used to test a 6.5 mm cancellous bone screw and a 12.7 mm hip compression screw. The holding power was higher in screws with a long or wide thread. Generally, the holding power in bones from females was about 70 per cent of that in bones from males.