OBJECTIVE: Evident association between elevated red cell distribution width (RDW) and ultrasonic parameters of both systolic and diastolic heart dysfunction exsists. We aimed to further investigate the associations of RDW in patients who suffered from ST-elevation myocardial infarction (STEMI) and to evaluate its predictive properties regarding systolic and diastolic dysfunction. METHODS: A total of 89 patients with STEMI were prospectively analysed. RDW was obtained at the time of STEMI and compared to the parameters of systolic and diastolic dysfunction obtained by transthoracic heart ultrasound on the fifth through seventh day post- STEMI. We also compared laboratory data and clinical outcome with RDW. RESULTS: The median RDW was 13,9%, and among other factors, RDW was significantly associated with older age (P<0,001), arterial hypertension (P=0,017), hyperlipoproteinaemia (P=0,037), non-smoking (P=0,027), increased Thrombolysis In Myocardial Infarction score (P=0,004) and multi-vessel disease (P=0,007). A higher RDW was observed in patients with parameters that indicated systolic and diastolic dysfunction (ejection fraction of the left ventricle (EFLV) <50% (P=0,009), early/late diastolic filling wave ratio (E/A) <1 (P=0,001), ratio of peak early transmitral velocity and early diastolic annular velocity (E/E’) >10 (P<0,001) and combined E/A<1 and E/E’>10 (P<0,001)). The best discriminatory properties were observed for combined E/A<1 and E/E’>10. RDW remained significantly associated with the aforementioned parameters in a series of multivariate regression models. CONCLUSION: Elevated RDW is significantly associated with the parameters of systolic and diastolic dysfunction even after adjusting for several confounding factors in the setting of STEMI and subsequent percutaneous coronary intervention. RDW seems to be better at discriminating patients with diastolic rather than systolic dysfunction. Comparing with other inflammatory biomarkers, RDW remained the strongerst predictor of systolic (P=0.016) and diastolic dysfunction (P=0,004 for combination of both ratios E/A and E/E’). Patients with elevated RDW suffer more often from atrial fibrillation and heart failure after STEMI.