With the development of the technology of electrophysiological study and radiofrequency catheter ablation, electrophysiologists realized that the coronary sinus (CS) was involved in several types of arrhythmias due to its special anatomic and histological characteristics. In this article we review the anatomy, histology and electrophysiology of the CS and the relation between the CS and selected types of arrhythmias. With the development of the technology of electrophysiological study and radiofrequency catheter ablation, electrophysiologists realized that the coronary sinus (CS) was involved in several types of arrhythmias due to its special anatomic and histological characteristics. In this article we review the anatomy, histology and electrophysiology of the CS and the relation between the CS and selected types of arrhythmias.