Anemia is generally accepted name for the reduced number of red blood cells in the circulation, a reduced amount of blood in the body and reduced hemoglobin in red blood cells. The erythrocytes are blood cells that are used to transport oxygen and carbon dioxide in the body. Anemia is not a disease itself, but describes the condition of the body or the existence of the disease. Anemia can be very exhausting and serious disease that can seriously affect the life of a patient. This thesis will discuss the classification of anemia, the etiology and morphological division of anemia, symptoms, signs, diagnosis, treatment, and also the possible complications of the disease and health care. An insight to a process that caused anemia can be given based on the ethiopathogenesis. Also existence of anemia is based on the anamnesis, the conversation with the patient about his problems, medical examination and making the blood test. Approaches to treating anemia are different and depend much on the cause. The doctor determines the strategy of treatment, such as the application of certain drugs and change of eating habits.