What Is a Hematologist?

Medically Reviewed by Jennifer Robinson, MD on September 20, 2023
2 min read

Hematologists are internal medicine doctors or pediatricians who have extra training in disorders related to your blood, bone marrow, and lymphatic system. They’re specialists who may work in hospitals, blood banks, or clinics. Hematologists who practice in labs are called hematopathologists. They’re trained in pathology, a branch of medicine that examines body tissues and blood with microscopes or tests.

All hematologists have at least 9 years of medical education. It includes 3 years of on-the-job training called residency after medical school and up to 4 years of subspecialty training. Some hematologists are generalists, while others focus on specific conditions and organs that require extra training.

You’ll most likely be referred to one by your primary care doctor. Reasons include if you have or might have:


No surprise: Hematologists spend a lot of time checking your blood. But they don’t just diagnose illnesses. They also do treatments, such as transfusing blood.

Complete blood count. This common test helps your doctor diagnose or monitor your disease. Blood drawn from your vein or finger is checked for the levels and characteristics of all three types of blood cells, including platelets.

Prothrombin time. This and a similar test called partial thromboplastin time look for bleeding or clotting disorders. They also check how well your medications and treatments are working.

Blood transfusion. It replaces blood you’ve lost in surgery, an accident, or an illness

Chemotherapy. This is given by a specialist called a hematologist-oncologist. It infuses your body with chemicals to kill fast-growing cancer cells.

Bone marrow transplant. Also called a stem cell transplant, it replaces diseased stem cells from the spongy center of your bone with healthy cells from other parts of your body or from a donor.

Ablation therapy. Your hematologist uses heat, cold, a laser, or chemicals to destroy damaged tissue.

You may not always come face to face with your hematologist. They often work closely with your internist, pediatrician, oncologist, or other primary doctor to interpret your test results or to monitor your condition. A lab technician who takes your blood sample usually isn’t a doctor. Blood draws take only minutes. You may wait a few days to get your test results.

If you have a long-term blood-related condition, such as hemophilia, you probably will see them regularly.