This paper showed that an inhibitor of protein disulphide isomerase (PDI) can block thrombus formation. Quercetin-3-rutinoside — which was identified from a screen of ∼5,000 compounds — inhibited both platelet aggregation and endothelial cell-mediated fibrin generation. In mice, intravenous infusion or oral administration of quercetin-3-rutinoside blocked thrombus formation (which could be reversed by infusion of recombinant PDI). The authors suggest that PDI inhibitors could be used as an adjunct in thrombotic disorders that are not controlled by current therapies.