A medical laboratory or clinical laboratory is a laboratory where tests are carried out on clinical specimens in order to obtain information about the health of a patient in order to provide diagnosis, treatment, and prevention of disease. Clinical laboratories are thus focused on applied science, mainly on a production-like basis, as opposed to research laboratories that focus on basic science on an academic basis.

Medical laboratories vary in size and complexity and so offer a variety of testing services. More comprehensive services can be found in acute-care hospitals and medical centers, where 70% of clinical decisions are based on laboratory testing. Doctors offices and clinics, as well as skilled nursing and long-term care facilites, may have laboratories that provide more basic testing services. Commercial medical laboratories operate as independent businesses and provide testing that is otherwise not provided in other settings due to low test volume or complexity.