ABSTRACT This article provides a comprehensive overview of upper gastrointestinal (GI) endoscopic biopsies in the diagnosis of GI (gastric and duodenal) disorders. It discusses the normal histology of the oesophagus, stomach and duodenum and then delves into the common pathologies encountered in these regions, including reflux esophagitis, Barrett’s oesophagus, Helicobacter pylori gastritis, atrophic gastritis, celiac disease and more in details. The article also provides guidance on interpreting endoscopic biopsy findings, highlighting potential diagnostic challenges and offering practical tips. Through this article, we also try to increase awareness among pathologists about GI pathologies that are often missed because of lack of history and other reasons.