Introduction: Thrombosis (VTh) is a rare dangerous complication of pacemaker implantation (PM). The aim of the study was to determine the dynamics of change in selected thrombotic and inflammatory factors after PM. Material and methods: The study involved 81 patients (30 female, mean age: 71.1 years) with PM, divided into two groups. Group A (71 patients) consisted of patients without VTh, whereas group B (10 patients) comprised the patients with VTh. A transthoracic echocardiogram (TTE) and a venous ultrasound (VU) examination were performed. The levels of D-dimers, fibrinogen, tissue factor (TF), factor VII, plasminogen activator inhibitor-1 (PAI-1), interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were determined in the venous blood. After PM, the TTE and VU examinations were repeated at 6 and 12 months, and blood analyses were performed within 7 days after PM, and subsequently at 6 and 12 months. Results: In 10 patients of group B, symptomatic VTh occurred at a mean time of 13.06 months after PM. Initially, the levels of IL-6, hsCRP, D-dimers, fibrinogen, TF, VII factor and PAI-1 were considerably higher in group B than in group A. In all patients the levels of these factors kept on increasing for up to 7 days after the procedure. In group A they subsequently decreased, whereas in group B they continued to rise. Conclusions: Increased levels of inflammatory and thrombotic factors were observed in patients with VTh before and after PM. The factors of highest risk of VTh occurrence were D-dimers, fibrinogen and TF.