Gastroenterologists are medical doctors who specialize in the diagnosis and treatment of diseases of the digestive system, such as hepatitis, ulcerative colitis, Crohn's disease, and colon or rectal cancer.

Gastroenterologists may perform many specialized tests, such as endoscopy, to diagnose or treat diseases. When necessary, they may consult with surgeons. Gastroenterologists may further specialize in treating people in certain age groups, such as pediatric gastroenterologists, who only treat children.

Gastroenterologists can be board-certified by the Board of Internal Medicine, which is recognized by the American Board of Medical Specialties.