Atrial fibrillation (AF) is one of the most common arrhythmias, especially in elderly subjects. During the last decade, the contribution of genetic factors in pathogenesis of AF has been focused. Three categories of genetic patterns are considered to relate to AF: (1) familial AF as a monogenic disease, (2) familial AF presenting in the setting of another inherited cardiac diseases (hypertrophic cardiomyopathy, dilated cardiomyopathy, familial amyloidosis) or another inherited arrhythmic syndromes (congenital long QT syndrome, short QT syndrome, Brugada syndrome), and (3) non-familial AF associated with genetic backgrounds that may predispose to AF, such as a polymorphism in the ACE gene. More recently, the genome-wide association study (GWAS) has identified several genomic regions associated with AF. In this review article, genetic backgrounds underlying familial and non-familial AF will be discussed.