Abstract The adsorption of Sendai virus to liposomes of different compositions was studied. Liposomes prepared with only phosphatidylcholine and cholesterol, and liposomes prepared with phosphatidylcholine and cholesterol plus phosphatidic acid or phosphatidyl serine did not adsorb virus. Phosphatidyleholine-cholesterol liposomes containing also stearyl amine or ganglioside did, however, adsorb virus. The ability of the adsorbing liposomes to compete with erythrocytes for virus was measured by hemagglutination inhibition. Liposomes containing ganglioside, but not those containing stearyl amine, inhibited hemagglutination. When the molar ratio of ganglioside N -acetyl neuraminic acid to phosphatidylcholine was less than 0.02, ganglioside liposomes did not inhibit hemagglutination. As the ratio increased from 0.02 to 0.05, the liposomes caused increasing amounts of hemagglutination inhibition, but with further increases in the ratio the hemagglutination inhibition remained constant. It is concluded that gangliosides can serve as Sendai receptors and that a multiplicity of receptors is needed for virus binding.