The treatment of retinal thrombosis is an unresolved problem, mainly because of the numerous factors which participate in their formation; modifications in the walls of veins and arteries, external compressions, changes in the blood count--particularly of the platelets--slowing down of the blood flow, increase in blood viscosity etc. No drug provides constant results. Some widely employed drugs such as vasodilators may be useless or even contra-indicated. Emphasis is placed on anti-coagulants, fibrinolytics, antiaggregating agents and methods of lowering blood viscosity. Their action is difficult to test objectively. Some do appear to be useful, especially in cases of central vein thrombosis. Thrombi of branches of the central vein are apparently inacessible to medical therapy, but occasionally improvement is seen after laser coagulation. This seems to apply also to hemorrhagic glaucoma secondary to retinal obstruction.