Concurrent measurements of combined cortical thickness (CCT) at the midshaft of the second metacarpal and at the proximal juxtametaphyseal radial cortex were made in 234 healthy women aged 46-80 years (group 1) and in 52 women with symptomatic osteoporosis (at least two spontaneous vertebral compressions) (group 2). When -2 standard deviations (SDs) of the mean values in young healthy women (aged 21-45 years) were used as the lower limit of normal measurements, 47% of the subjects in group 1 showed abnormalities: in 25% both bones were abnormal, in 12% the radius alone was abnormal, and in 10% the second metacarpal alone was abnormal. Because 98% of the subjects in group 2 had abnormal CCT measurements, the -2-SD limit of the younger healthy subjects appears to constitute a satisfactory "fracture threshold." Although further research and correlation are required, these simple and inexpensive measurements may be appropriate for mass screening to separate those at greater risk for development of spontaneous vertebral compressions from those at lesser risk.