Atrial fibrillation (AF) is a major public health burden worldwide, and its prevalence is set to increase owing to widespread population ageing, especially in rapidly developing countries such as Brazil, China, India, and Indonesia. Despite the availability of epidemiological data on the prevalence of AF in North America and Western Europe, corresponding data are limited in Africa, Asia, and South America. Moreover, other observations suggest that the prevalence of AF might be underestimated-not only in low-income and middle-income countries, but also in their high-income counterparts. Future studies are required to provide precise estimations of the global AF burden, identify important risk factors in various regions worldwide, and take into consideration regional and ethnic variations in AF. Furthermore, in response to the increasing prevalence of AF, additional resources will need to be allocated globally for prevention and treatment of AF and its associated complications. In this Review, we discuss the available data on the global prevalence, risk factors, management, financial costs, and clinical burden of AF, and highlight the current worldwide inadequacy of its treatment.