Hemoglobin was purified from the outdated human red blood cells. Phospholipids were purified from egg yolk and stored in chloroform. The artificial red blood cells (hemosome) were prepared by encapsulation of hemoglobin with phospholipid mutilayer using rotary vacuum evaporator. The shape and size of hemosomes were measured by phase contrast microscope and image analyzer. The function of hemosomes was tested by measuring oxygen dissociation curve using blood gas analyzer. In order to test whether hemosomes are useful as blood substitute they were infused into rats of which one third of total blood were drawn. The results obtained are summarized at followings. 1) Hemosomes were spherical shape and their mean diameter was 0.7 um. 2) Oxygen dissociation curve of hemosomes showed the same figure as that of normal red blood cells. 3) All rats given 1/3 transfusion with hemosomes survived until sacrificed whereas three of four rats given 1/3 transfusion with saline died within 1 hour and the rest of them died within 24 hours.