To the Editor: We report here the first therapeutic use of an experimental, oxygen-transporting blood substitute, Fluosol-DA 20%. It is made and supplied by the Green Cross Corporation (1–47, Chuoh 1–chome, Joto-ku, Osaka, Japan), whose records confirm this case as its initial clinical use. Its active ingredients (perfluorodecalin and perfluorotripropylamine) give this biologically inert emulsion a high oxygen-carrying capacity of 7.2 volumes per volume at 37°C; the oxygen-carrying capacity of red cells is 17 to 20 volumes per volume. The safety and efficacy of Fluosol have been demonstrated in wide and comprehensive studies in animals, in decerebrate human subjects, and . . .