OBJECTIVES: Atrial fibrillation (AF) is the most common arrythmia whose prevalence increases significantly with age. Few epidemiological studies give prevalence stratified by age classes. In order to evaluate disease burden it is crucial to estimate AF prevalence by specific age and quantify subjects with AF over Italian population. METHODS: Published epidemiological studies in which prevalence by age is reported were searched. Italian studies were privileged and International literature considered only if quoted in Italian guidelines. For each selected study prevalence was estimated by best fitting a logistic function for increasing age classes. Age-specific prevalence was then calculated for each year of age and related to Italian population age distribution to estimate the number of AF cases. RESULTS: Quoted in AF Italian Guidelines, CASTEL, Framingham and ATRIA studies give prevalence stratified by increasing age classes. For each study the logistic function gave the best fit, and provided very similar fitting parameters. Reported prevalence for Framingham study are 0.5% for 50-59 years, 1.8% for 60-69 years, 4.8% for 70-79 years, 8.8% for 80-89 years while those estimated by the fitting are 0.8%, 2.1%, 4.6% and  8,6% respectively. Projecting the estimated prevalence over the entire Italian population (58.6 millions), 761,438 AF cases (CL95% 540,022 – 1.058.308) are estimated to be distributed within age ranges as follows: 28,718 in