Hematology is the branch of medicine concerned with the study, diagnosis, treatment, and prevention of diseases related to the blood. It involves treating diseases that affect the production of blood and its components, such as blood cells, hemoglobin, blood proteins, and the mechanism of coagulation.

Hematologic diseases are disorders which primarily affect the blood. Common disorders include anemia, sickle cell disease, lymphomas, leukemia, and hemophilia.