The human gastrointestinal (GI) tract, a complex, interconnected system that plays a vital role in digestion, absorption, and metabolism, is susceptible to a myriad of disorders that manifest in various pathological changes. This chapter, “Pathology of the Gastrointestinal Tract,” offers an in-depth exploration of the broad spectrum of diseases that affect the GI tract, their gross and microscopic pathological features, and how these appearances can guide our understanding of disease mechanisms.