Roentgenograms of the lateral lumbar area of the spine were obtained from 1,015 subjects over age 45 who were residing in North Dakota. Three hundred lived in an area where the fluoride content of the water supply was high, 4 to 5.8 ppm, and 715 in an area where it was low, 0.15 to 0.3 ppm. Evidence of osteoporosis, reduced bone density, and collapsed vertebrae was substantially higher in the low-fluoride area, especially in women. Visible calcification of the aorta was significantly higher in the lowfluoride area, particularly in men. Limited information on milk and cheese consumption does not indicate that differences in calcium consumption are a significant factor. Fluoride consumption is important in the prevention of osteoporosis and may also play a significant role in preventing calcification of the aorta.