Internal medicine or general internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of internal diseases that affect the internal organs of the body such as the heart, liver, kidneys etc.

An internal medicine doctor (internist) is a physician who provides long-term, comprehensive care, managing both common and complex illnesses of adolescents, adults, and the elderly.

Internal medicine doctors treat patients for a variety of diseases which include: infections, and nonsurgical diseases affecting the heart, blood, blood vessels, kidneys, joints, and the digestive and respiratory systems.