The objective of the study is to determine the prevalence of a plan, its impact on quality of life, dependence and functional limitation in a random population of 40 years and over. Cross-sectional study in a random population sample in Cambre (A Coruña-Spain) (n = 835) (α = 0.05; precision = ±3.4%). Anthropometric variables are studied, comorbidity (Charlson Score), foot functionality (FFI questionnaire), foot health questionnaire (FHSQ), quality of life (SF-36) and dependence on activities of daily living (Barthel index and Lawton). A logistic and linear multiple regression analysis was performed. The prevalence of flat feet was 26.62%. Patients with flat feet presented higher: age (65.73 ± 11.04 years), comorbidity index (0.92 ± 1.49), BMI (31.45 ± 5.55) and foot size (25, 16 ± 1.66 cm). Having flat feet decreases the quality of life and function of the foot. The association of flat feet with age, Charlson index, and BMI and foot size was found. The SF-36, Barthel and Lawton questionnaires remained unchanged due to the presence of the flat foot, a difference between the FHSQ and FFI that were significantly sensitive.