153 patients with a trochanteric hip fracture were operated on with a compression hip screw (CHS) and followed for 4 months. They were randomized into 2 groups, with or without a key and compression of the lag screw. Greater sliding of the lag screw was noted in cases where the compression screw and the key were used, especially in women over 80 years of age and in patients with a previous fracture indicating osteoporotic bone. Use of a key and compression of the lag screw gave no advantage, and we do not recommend this for treatment of trochanteric hip fractures.