Gastroenterology is concerned with the digestive system and its diseases.

Gastroenterologists diagnose and treat diseases of the oesophagus (gullet), stomach, small and large intestines, rectum and anus, as well as certain digestive glands (liver, biliary ducts and pancreas, as these secrete certain digestive enzymes).

Hepatology represents a separate discipline of gastroenterology; it is concerned with the liver and its diseases (hepatitis, cirrhosis of the liver and liver cancer).