We report a case of atrioventricular (AV) reentrant tachycardia with ostial atresia of the coronary sinus (CS). On levophase coronary venogram, dual anomalous venous drainage into both atria was seen; no ostium of the CS and no persistent left superior vena cava were noted. Based on mapping, radiofrequency (RF) energy was applied at the mitral ring and the bypass tract was eliminated. Eight months after the procedure, the patient has remained completely symptom-free.