Anemia, an insufficiency of red blood cells (RBC) and hemoglobin for oxygen-carrying needs, results from a variety of disease processes, some of which must have existed since ancient times. It was defined in quantitative terms in the mid-nineteenth century, but before that the evidence of anemia is found in the descriptions of pallor or in the occurrence of diseases that we now know cause anemia. For example, lead poisoning decreases RBC production and was apparently widespread in Rome. Intestinal parasites cause iron deficiency anemia and were known to exist in ancient times. Parasites found in paleopathological specimens include Ascaris lumbricoides, Trichiuris trichiuria, and various species of Taenia (ovis, globosa, solium, and saginata), all of which can cause intestinal blood loss and anemia. Diphyllobothrium latum, which leads to malabsorption of vitamin B12 and a megaloblastic anemia, has been found in mummies in Prussia and Peru.

Congenital abnormalities in RBC metabolism, including glucose 6-phosphate dehydrogenase (G6PD) deficiency and various forms of thalassemia and sickle-cell disease, were probably present also in ancient times. Thalassemia protects against malaria, and the incidence of the relatively mild, heterozygotic form of thalassemia (thalassemia minor) probably increased in the Mediterranean region after the appearance of falciparum malaria, the most fatal form of the disease.