Introduction: Patients with heart failure (HF) display elevated levels of soluble fractalkine, a chemokine involved in inflammation processes, atherosclerosis and platelet activation. Further, fractalkine has been associated with reduced pharmacodynamic (PD) responsiveness to clopidogrel. The aim of this study was to investigate the association of fractalkine with the severity of HF and its impact on platelet activation and clopidogrel response in patients with coronary artery disease (CAD) with and without HF. Materials and methods: This prospective PD study included 116 stable CAD patients on DAPT with aspirin and clopidogrel. Subjects were classified in two groups: patients with HF and reduced (<40%) left ventricular ejection fraction (HFrEF group, n = 56) and patients without HF (no HF group, n = 60). Clinical severity of HF was graded according to NYHA classification. Platelet function assays included vasodilator-stimulated phosphoprotein assay, multiple electrode aggregometry and light transmittance aggregometry. Fractalkine and P-selectin concentrations were determined by ELISA. Results: Fractalkine levels progressively increased with the severity of the disease in the HFrEF group (NYHA I: 471.2 ± 52.4 pg/ml, NYHA II: 500.5 ± 38.4 pg/ml, NYHA III: 638.9 ± 54.3 pg/ml, p for linear trend 0.023). Numerically higher concentrations of fractalkine were observed in the HFrEF group compared to the no HF group with borderline significance (p = 0.052). No significant differences in clopidogrel-induced platelet inhibition according to fractalkine values were observed in any of the groups. Conclusions: Fractalkine levels were increased in patients with HFrEF and positively associated with the functional severity of the disease. No evident impact of fractalkine on clopidogrel PD efficacy was found.