Kumlin, T., Wiikeri, M., and Sumari, P. (1973).Brit. J. industr. Med.,30, 71-73. Radiological changes in carpal and metacarpal bones and phalanges caused by chain saw vibration. We have made a radiological examination of the shoulder and elbow joints, wrists, and hand bones of 35 lumberjacks, 30 of whom had used a chain saw for 7 to 20 years. Their average age was 43·9 years. Thirty-one men (89%) had a history of typical attacks of Raynaud's phenomenon. In seven cases (20%) with 10 to 18 years' exposure to chain saw vibration, the radiographs revealed vacuoles (defined in the paper) in the hand region, all between the styloid process of the ulna and the phalanges. The vacuoles are considered to be typical skeletal changes caused by long use of the chain saw. In the control group, which consisted of persons matched for age with the lumberjacks and who had never been exposed to vibration, no exactly corresponding changes were found. The nature and frequency of these findings are in keeping with similar results of other authors.