To estimate changes in the age- and gender-specific prevalence of Paget's disease in Britain, we performed a radiographic survey of the disorder in 10 British centers, using sampling and radiographic methods identical to a study performed in 1974. In each center, a sample of abdominal radiographs of people aged 55 years and over was taken from stored films within the radiology department of the principal general hospital. The radiographs were identified by screening radiographic records over the period 1993-1995. Any abdominal radiograph in a subject aged 55 years and over which included the entire pelvis, sacrum, femoral heads, and all lumbar vertebrae was studied. The radiographs were evaluated by a trained observer and the consultant radiologist who participated in the original 1974 survey. Nine thousand eight hundred and twenty-eight radiographs (4625 men, 5203 women) were assessed in the 10 towns. The overall age/gender standardized prevalence rate was 2%, with a male/female ratio of 1.6. Prevalence increased steeply with age among men and women, rising to 6.9% of men and 5.8% of women aged 85 years and over. The prevalence of Paget's disease in the 10 towns in 1994 was only 40% of that observed during the 1974 study. The decline in prevalence was apparent in all 10 centers, but was most marked in those with high rates in the original study. This survey of Paget's disease in 10 British towns suggests a prevalence of 2.5% among men and 1.6% among women aged 55 years and over. Age-adjusted prevalence rates declined steeply between 1974 and 1994. These declines suggest an environmental contribution to the etiology of this disorder that requires further investigation.