: Recent studies reveal that neutrophil extracellular traps (NETs) play a significant role in platelet entrapment and consequent activation of the coagulation cascade. Herein we present two autopsy cases of NETosis. The first case is a 76-year-old man, with metastatic squamous cell carcinoma of the lung who expired 5 days post admission. Autopsy revealed extensively necrotic poorly differentiated squamous cell carcinoma of the right lung. A 30-cm cylindrical thrombus was identified, extending from the left ventricle to the thoracic aorta, composed of numerous neutrophils enmeshed in abundant fibrin representing a NET. The second case is a 73-year-old man who suffered a cardiopulmonary arrest of unknown cause and expired 2 days post admission. Autopsy revealed a 5-cm mural thrombus with numerous neutrophils in the descending aorta consistent with NET, bilateral bronchopneumonia and infarcted bowel. These two autopsies highlight the pathogenic role of NET in causing thrombosis.