SummaryA single infusion of a fat emulsion, Intralipid®, used for parenteral nutrition was given to 11 healthy normals, 3 patients with von Willebrand’s disease and 3 with mild or moderately severe thrombasthenia. The infusion had no effect on coagulation or the fibrinolytic system. Platelet adhesiveness, as determined with Hellem’s whole blood method, was markedly increased but not with his plasma-ADP method or with Salzman’s method. No shortening of the bleeding time was observed in the normals or in the patients with prolonged bleeding time. The change observed in platelet adhesiveness is therefore believed to be an in vitro artefact with no clinical relevance.