Gastrointestinal pathology is the sub-specialty of surgical pathology. It primarily focuses on the diagnosis, treatment and characterization of neoplastic and non-neoplastic diseases of the digestive tract and other accessory organs. The digestive tract or the gastrointestinal (GI) tract is the passage for the transport of food and absorption of nutrients. Gastrointestinal pathology involves the diagnostic evaluation of surgical organs and biopsy pathology of gastrointestinal tissues. Its physiology, disease mechanisms and histomorphology also fall under its focus areas. The two major symptoms associated with it are abdominal pain and gastrointestinal hemorrhage. The diagnosis of abdominal pain depends on the length of the time of the pain. The causes of this pain are inflammation, perforation, obstruction and vascular diseases. The diagnosis of upper gastrointestinal bleeding is possible with endoscopy, while the diagnosis of a lower gastrointestinal bleeding requires colonoscopy or sigmoidoscopy. This book provides significant information of this discipline to help develop a good understanding of gastrointestinal pathology and related fields. It will also provide interesting topics for research which interested readers can take up. Those in search of information to further their knowledge will be greatly assisted by this book.