Medical laboratory technologists and technicians typically do the following:

• Analyze body fluids, such as blood, urine, and tissue samples, and record normal or abnormal findings
• Study blood samples for use in transfusions by identifying the number of cells, the cell morphology or the blood group, blood type, and compatibility with other blood types
• Operate sophisticated laboratory equipment, such as microscopes and cell counters
• Use automated equipment and computerized instruments capable of performing a number of tests at the same time
• Log data from medical tests and enter results into a patient's medical record
• Discuss results and findings of laboratory tests and procedures with physicians
• Supervise or train medical laboratory technicians

Both technicians and technologists perform tests and procedures that physicians and surgeons or other healthcare personnel order. However, technologists perform more complex tests and laboratory procedures than technicians do. For example, technologists may prepare specimens and perform detailed manual tests, whereas technicians perform routine tests that may be more automated. Medical laboratory technicians usually work under the general supervision of medical laboratory technologists or laboratory managers.

Technologists in small laboratories perform many types of tests; in large laboratories, they sometimes specialize. The following are examples of types of specialized medical laboratory technologists:

Blood bank technologists, or immunohematology technologists, collect blood, classify it by type, and prepare blood and its components for transfusions. 

Clinical chemistry technologists prepare specimens and analyze the chemical and hormonal contents of body fluids. 

Cytotechnologists prepare slides of body cells and examine these cells with a microscope for abnormalities that may signal the beginning of a cancerous growth. 

Immunology technologists examine elements of the human immune system and its response to foreign bodies. 

Microbiology technologists examine and identify bacteria and other microorganisms. 

Molecular biology technologists perform complex protein and nucleic acid tests on cell samples.

Like technologists, medical laboratory technicians may work in several areas of the laboratory or specialize in one particular area. For example, histotechnicians cut and stain tissue specimens for pathologists, who are doctors who study the cause and development of diseases at a microscopic level.

Technologists and technicians often specialize after they have worked in a particular area for a long time or have received advanced education or training in that area.