A 65 yrs-old male patient (pt) underwent, because of symptomatic sick sinus syndrome, a dual-chamber pacemaker (PMK) (Boston Advantio DR) implantation with atrial and ventricular passive fixation leads inserted through the left cephalic vein. The procedure was not complicated, with good atrial and ventricular sensing (AVS) and pacing threshold (AVT). At discharge, warfarin was prescribed because of persistent atrial fibrillation. Two months later patient complained left latero-cervical neck tumour, with pain and dysphagia. The diagnosis was a left internal jugular vein (IJV) thrombosis caused by a lead loop in correspondence of left subclavian vein origin (figure.1, figure.2). AVS and AVT where normal. The extraction leads procedure was unsuccessful and a new implant in contralateral subclavian vein was performed. In literature there are only four cases of IJV thrombosis following a permanent PMK implant. It’s important to keep in mind this possible complication in order to make an early diagnosis. Pain, dysphagia and lateral swelling tumour can suggest IJV diagnosis in order to restore the vein flow using antithrombotic drugs (i.e. heparin infusion) and/ or explanting the leads. FIGURE 1 Neck and thoracic contrast tomography showing a lead loop in correspondence of left subclavian vein origin.