At two x ray examinations in 1957 and 1967, 17 cases of skeletal fluorosis were identified among long term cryolite workers in Copenhagen. In 1982 four of these patients were alive, eight to 15 years after exposure had ended. Radiographs were obtained, and the urinary fluoride excretion was measured. A similar picture emerged in all four cases: extensive fading of the sclerosis of trabecular bone in ribs, vertebral bodies, and pelvis, whereas cortical bone thickening and calcification of muscle insertions and ligaments remained virtually unchanged. The fluoride excretion was increased in three cases (with the shortest exposure free period). These findings indicate that with continuous remodelling of bone tissue trabecular sclerosis is slowly reversible and the excess fluoride is excreted in the urine.