A population survey was performed to estimate the prevalence of vertebral fractures in women aged 45-69 and to determine their relationship to bone density and symptoms. Subjects were 1035 women aged 45-69 (mean 55.4 years, response rate 77%) from the age-sex register of a large 11,000-person general practice in Chingford, London. Thoracic and lumbar spine x-rays were read by a semiautomated quantitative method. Vertebral fractures were diagnosed using a variety of morphometric methods, including a new method we recently developed and the published methods of Melton and Eastell. These methods all detect abnormal ratios between anterior, central, or posterior vertebral height and between observed posterior vertebral height and values predicted from the posterior height of adjacent vertebrae. Bone mineral density (BMD) of lumbar spine L1-4 and neck of femur was measured by dual-energy x-ray absorptiometry (DXA). Using our method, 147, 14.2% (95% CI 12.0-16.2%) of the 1035 women, had minor fractures (at least two vertebral ratios 2-2.99 SD below the mean) and 20, 1.9% (95% CI 1.2-3.0%) of the total, had severe fractures (at least two ratios more than 3 SD below the mean). In the 147 women with minor fractures, bone density of the spine was not significantly lower than in the other 868 women, and reported back pain or loss of height was no more common. Women with multiple minor fractures did have lower bone density, by 0.4 SD. In the 20 women with severe fracture, bone density was significantly lower, by 0.6 SD.(ABSTRACT TRUNCATED AT 250 WORDS)