Platelet contamination in stored plasma may affect coagulation assays, including the endogenous thrombin potential (ETP), which has been proposed for the investigation of hyper- and hypo-coagulability. The current recommendation of filtering plasma before freezing cannot be always met. This study provides evidence that filtering frozen plasma after thawing, prior to testing, may help to eliminate the unwanted effect of residual platelets on the ETP. This may have important implications in future studies, as the ETP could be determined with plasma that have been collected without precautions relating to platelet contamination, as is the case for plasmas collected in epidemiological studies.