The aim of this study was to ascertain the prevalence and severity of vertebral fractures in French elderly women. We used spinal radiographs collected during the baseline examination of the Epidémiologie de l'Ostéoporose (EPIDOS) study, a multicentric prospective study of risk factors for hip fracture. A total of 7598 ambulatory women volunteers were recruited in the EPIDOS cohort using large population-based listings such as voter-registration lists. A subsample of 770 participants were selected for spinal radiographs using a systematic selection procedure. Anteroposterior and lateral radiographs of the thoracic and lumbar spine were reviewed by two trained rheumatologists using the semiquantitative (SQ) method described by Genant et al. [J. Bone Miner Res. 8 (1993) 1137]. Vertebral deformities that could be related to causes other than osteoporosis (i.e., Scheuermann's disease or osteoarthritis) were disregarded. The final analysis was made over 745 women after excluding 25 women whose spine radiographs were incomplete or of poor quality. The sample average age was 80.1 +/- 3.4 years. Vertebral fractures were found in 170 women: 22.8% (95% CI, 19.8-25.8%). A single, two, three, or more vertebral fractures were seen in 99 (58.2%), 43 (25.3%), and 28 (16.5%) of the 170 affected women, respectively. The prevalence of vertebral fractures increased with age from 19.0% (95% CI, 14.9-23.1%) among women 75-79 years old to 21.9% (95% CI, 17.3-26.5%) among those 80-84 years old and to 41.4%(95% CI, 31.0-51.7%) among those 85 years of age and over (Chi-square test for trend P < 0.00016). A significant correlation was found also between the number of vertebral fractures per woman and age (r = 0.108, P = 0.003) and between the spinal fracture index and age (r = 0.105, P = 0.004). We conclude that the prevalence of vertebral fractures is high in French ambulatory elderly women, which confirms the results of previous studies conducted in various Caucasian and Asian populations.