Atrial fibrillation (AF) remains one of the most common and challenging arrhythmias encountered in clinical practice. While familial forms had remained mostly unknown, in this last decade, the identification of genetic defects, which mainly affect ionic currents, has been the key in our understanding of the pathophysiology of the inherited form of the arrhythmia. Despite the limited prevalence of the familial disease, elucidation of the molecular mechanisms that cause familial AF will likely facilitate understanding of the more common acquired forms of the disease. Therefore, as data keep unravelling, clinicians can expect that soon better therapeutic and preventive options for this arrhythmia will emerge from the discoveries in basic science.