The identification of the first gene locus of hereditary arrhythmias was made over 10 years ago. In the last few years, considerable progress has been made and the number of culprit genes for cardiac arrhythmias has rapidly increased. This has been the fruit of close collaboration between clinicians, geneticists and physiologists. This work has demonstrated the heterogenous nature of genetics of diseases. It has led to a better understanding of underlying physiopathological mechanisms by the study of the relationship between gene and clinical abnormalities. In addition, analysis of phenotypes and genotypes has improved our knowledge of the clinical presentation of diseases and opened up new therapeutic approaches. These new diagnostic methods have enabled preventive measures to be taken to avoid potentially serious arrhythmias. The genetics of cardiac arrhythmias is still in its infancy: many culprit genes remain undetected and their identification should led to considerable progress in the understanding of the physiopathology of arrhythmias and their treatment.