Background Dyspepsia is one of the most common GI complaints encountered in clinical practice. Histopathological assessment of endoscopic gastric mucosa biopsy is crucial to delineate the exact cause of dyspepsia to guide patients' management. Objectives The aim of this study was to determine the histopathological spectrum of upper gastrointestinal (GI) tract endoscopic biopsies and to study the age and sex distribution of the predominant upper GI lesions. Methods A cross-sectional study was conducted in the Department of Pathology, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India, from January 2022 to December 2023. All endoscopic mucosal biopsies of the esophagus, stomach, and duodenum (first and second parts) lesions were examined under a microscope for histopathological findings. Results Out of 250 endoscopic biopsies studied, there were 76 cases of esophageal biopsies, 149 cases of gastric biopsies, and 25 cases of duodenal biopsies. The male-to-female ratio was 1.2:1. Non-neoplastic lesions were more common than neoplastic lesions. The most common lesions encountered were esophagitis in the esophagus, gastritis in the stomach, and duodenitis in the duodenum. Conclusion The main organic cause of dyspepsia in our setting was chronic gastritis. We conclude that endoscopy of the upper GI tract and histopathological examination help in the earlier detection of both benign and malignant lesions. This aids in better timely management of the patients and improves the overall treatment provided resulting in a better prognosis.