The Prospective Epidemiological Risk Factor (PERF) Study is an ambidirectional population-based study of postmenopausal women set up with the purpose of obtaining a better understanding of the aetiology and pathogenesis of age-related diseases. Participants were recruited from a source population of 8875 women residing in Denmark. The baseline examination (PERF I) comprised 5855 women with mean age of 70.8 years (49.7-88.8) and took place between 1999 and 2001. All subjects have been followed up with registry linkage using population-based national registries. Further, a subcohort was re-invited to attend a follow-up visit between 2013 and 2014 (PERF II). Registry data are available for all baseline participants. From the baseline population, 2103 were enrolled in PERF II.