Bone Paget's disease is heterogeneously distributed and several foci of high prevalence have been reported in Spain. The aim of the present work was to determine the prevalence of the disease in a zone situated in the northwestern sector of the Province of Salamanca (Spain) using a cross sectional epidemiological study. Sample choice was based on a stratified sampling according to the residence, age and sex of the inhabitants of the zone. A sampling error of 5% and a confidence level of 95% were considered; these afforded a sample of 378 units. Final choice of the subjects was based on a random pathway method. Data collection was accomplished with a personal interview using a 31-item questionnaire and analytical screening (AP and GGT). The field work was carried out over a one-year period. The data were input onto a calculation sheet for analysis and epidemiological interpretation. Finally, clinico-radiological confirmation of the cases deemed positive in the screening was accomplished. The prevalence of PBD in the zone studied is 5.7% (95% CI: 4.5–6.9). The highest percentage of patients lies within the age group between 70–79 years; most of these patients were women. The mean residence time in the zone was 66 years. According to the findings, this geographic zone has a high prevalence of PBD.