Abstract: Carrier erythrocytes are one of biological drug delivery systems have been investigated in recent years. They are biocompatible, biodegradable as well as they have long life span. This review deals with criterion, requirement and methods of drug loading as well as characterizations, safety and application of erythrocyte as drug delivery system. The drugs with high toxicity, such as cardiotoxic and neurotoxic are selected to be encapsulated in the erythrocytes because of their potential for delivery to the liver, spleen and lung. Physical methods like endocytosis and osmotic based methods are used for drug loading into erythrocytes, as well chemical methods are used for the same purpose. After loading of therapeutic agent on erythrocytes, the carrier cells are exposed to physical, cellular as well as biological characterizations. The resealed erythrocytes were used either for sustained release or targeted release of therapeutic agents. The targeted resealed erythrocytes are structurally modified either by glutaraldehyde, oxidizing agents or by drug itself. The modified carrier erythrocytes have tendency to be phagocytosed, therefore, they removed from the circulation and targeted to the organs of reticuloendothelial system.