It has been found in in vivo and in vitro experiments that, as a perfluorocarbon emulsion stabilized by Proxanol 268 comes in contact with blood plasma proteins, plasma proteins with molecular masses from 25 to 170 kDa and above are adsorbed on the surface of emulsion particles. Among the adsorbed proteins, fibronectin and fibrinogen were identified by immunoblotting. In in vivo experiments, during circulation in the blood flow, considerable amounts of plasma proteins are adsorbed on Proxanol-stabilized emulsion particles; the amount of adsorbed proteins increases with the time the particles are in the blood flow. Considerably lesser amounts of proteins are adsorbed during circulation in the blood flow on emulsion particles stabilized by egg yolk phospholipids, and their qualitative composition differs from the composition of proteins adsorbed on Proxanol-stabilized emulsion particles. A preliminary incubation of the Proxanol-stabilized emulsion with heparin decreases the amount of the adsorbed proteins and changes their qualitative composition.