Hematology is a branch of medicine that deals with the study of blood, and the causes, prognosis, treatments and prevention of blood-related diseases. Red blood cells are a specific type of blood cells, which are the primary means of transporting oxygen to the tissues in the body through blood flow. They transport oxygen to the lungs through the capillaries and then release it in the tissues. The cytoplasm of these cells consists of hemoglobin, which contains the iron biomolecule having the capability to bind oxygen. Hemoglobin also provides the red color to the cells and blood. The cell membrane of the red blood cells comprises lipids and proteins, which provides essential properties for various physiological functions of the cells. These functions include stability and deformability of the blood cells, while traversing the capillary network and circulatory system. The red blood cells are created by the process of erythropoiesis, in which stem cells are transformed into red blood cells. Red blood cells have clinical significance as diseases such as anemia, hemolysis, and polycythemia can occur due to low or high red blood cell count. This book contains some path-breaking studies on red blood cells and the diseases associated with them. It will serve as a resource guide for experts as well as students.