Clinical hematology is a field of medicine involving research, prevention, diagnostics and treatment of blood disorders. Blood cells are studied with respect to their composition, quantity and function. Hematology also focuses on coagulability and all factors that play a role in the coagulability of blood.

The basic methods of examination in hematology are analysis of blood, i.e. blood count, and bone marrow and examination of coagulation. Venous blood sampling is used for taking a basic blood count. The sample reveals the number, size and other properties of red and white blood cells and platelets. Based on these indicators, specialists diagnose blood-formation disorders, blood diseases, chronic inflammation, infectious diseases and autoimmune illnesses. Simple hematological tests can be used to determine, for example, blood type and blood coagulability (Quick test or PT test).

The most common diagnoses include disorders of the red blood-cell line such as anaemia of various origins, platelet quantity disorders and abnormalities in the quantity of white blood cells. Oncological diagnoses also fall under hematology and are addressed by the specialised hemato-oncology department.

A hematological examination is recommended by a general practitioner when a blood-formation or other blood disorder is suspected or by an outpatient specialist who is treating the given patient for a different condition.