The histo-pathologic features of experimental anaphylactic uveitis produced by an intravitreous injection of citrated human plasma and its following intravenous injection were outlined. The early changes in the retina were studied by the electron microscope with special emphasis on the earliest change of the pigment epithelium. Electron micrographs revealed that a constriction of the endoplasmic reticulum of the pigment epithelial cells followed by a dilatation on the endoplasmic reticulum and vacuolization was the earliest change in the retina. Electron micrographic pathologic features of the retina of the opposite eye 15 min. after the intravenous injection of 2 ml of human plasma 2 weeks after the intravitreous injection are also described.