5-Fu polyphase liposome was prepared by fusing the drug with lecithin and cholesterol, the rate of encapsulation being 52%, and 97% of the particles were less than 2 microns in diameter and stable against heat and cold. 5 mg of tritiated 5-Fu in 0.5 ml of the polyphase liposome preparation was injected subconjunctivally in rabbits. The concentrations of 5-Fu in the conjunctiva, the sclera, and the conjunctiva-Tenen's capsule-sclera en bloc 180 degrees from the site of injection were measured by the scintillation method 12, 24, 48, 72 and 96 hours after injection to be no less than 0.2 microgram, the ID50 of fibroblast proliferation. These findings suggested that 5-Fu polyphase liposome preparation might be substituted for 5-Fu solution in the filtering operation to reduce the frequency of injections and to attenuate the side effects.