There is considerable interest regarding subretinal fluid obtained at retinal detachment surgery. The variability of this fluid is well-known clinically, and according to Duke-Elder,1 the nature of the subretinal fluid depends upon whether or not a retinal hole is present. Two basic types of subretinal fluids are thus differentiated: Another interesting feature of the subretinal fluid is the characteristic change in this fluid which is said to occur with increasing age of the detachment. Thus, the density of subretinal fluid, although greater than that of the vitreous, is low in recent cases and increases with duration of the detachment. Similarly, the protein content of subretinal fluid, initially higher than that of the vitreous, is also said to increase with the duration of the retinal separation. In order to investigate further the subretinal fluid, a study of the electrophoretic pattern of this fluid has been done. The purpose of this paper is