Carp plasma lipoprotein was, in vitro, examined for the influences of lipid on electrophoretic behavior. The results obtained are as follows.
l) Plasma lipoproteins were combined with several kinds of lipid of different degrees. Their mobility changed under the influence of additional lipids, especially unsaturated fatty acids.
2) The additional lipids were preferentially accepted by carp plasma albumin which is a sort of lipoprotein, and consequently changed its mobility.
3) The difference of lipid composition in plasma lipoprotein as being the prosthetic group or the transported substance probably revealed the electrophoretic polymorphism of lipoprotein.