 Background Pulmonary embolism PE is a serious cardiopulmonary disorder caused by partial or complete obstruction of the pulmonary arterial bed by a thrombus formed in systemic veins. Pulmonary embolism is thought to be a result of the interaction between the patient and risk factors 1-3. In case of suspected PE, clinical, laboratory, and radiological findings should be carefully studied. Since the clinical findings in PE are non-specific, objective diagnostic tests are required for the diagnosis 4. Computed tomographic pulmonary angiography CTPA is increasingly being used as the first investigation for suspected PE. The extent of PE is commonly expressed by indicating the anatomical level of the most proximal vessel affected by a thrombus 5. For the definite diagnosis of suspected PE, one of the tests to be used is the determination of the D-dimer level. Plasma D-dimer measurement provides information about fibrin-degradation fragment following fibrinolysis. D-dimer assays have low specificity, but high sensitivity and negative predictive value in most patients with suspected thromboembolism 6. The red cell distribution width RDW is a quantitative indicator of the size variability of red blood cells. This parameter can be easily obtained from a full blood count and is accepted as an indicator of ineffective red cell production 7. Some studies have suggested that RDW may be associated with cardiovascular and pulmonary diseases including PE 8-13. 