Red blood cells ( also known as RBCs , red blood corpuscles or erythrocytes ) are cells in the blood which transport oxygen . Red blood cells are also known as RBCs , red blood corpuscles ( an archaic term ) , haematids , erythroid cells or erythrocytes ( from Greek erythros for `` red '' and kytos for `` hollow '' , with cyte translated as `` cell '' in modern usage ) . Packed red blood cells , which are made from whole blood with the plasma removed , are used in transfusion medicine .