High Quality Content by WIKIPEDIA articles! Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. Physicians specializing in internal medicine are called internists. They are especially skilled in the management of patients who have undifferentiated or multi-system disease processes. Internists care for hospitalized and ambulatory patients and may play a major role in teaching and research. Although some internists are full-time hospitalists, many fulfill locum tenens (temporary) positions both stateside and internationally. Internal medicine is also a specialty within veterinary medicine.