We report a case of a patient with an additional great cardiac vein, discovered during the implantation for cardiac resynchronization therapy (CRT). Anomalies of the coronary sinus and its tributaries may cause difficulties in appropriate implantation of the left ventricular lead but they can also be considered as alternatives for lead placement. Although unusual angiogram of the coronary venous system, a left ventricular pacing lead was successfully placed in the left marginal vein. To settle diagnostic doubts, multislice computed tomography was carried out.