Aims: This study aimed to assess the relative telomere lengths (TLs) in gastric mucosa of patients infected with Helicobacter pylori (H. pylori) compared to H. pylori-negative controls and determine the effect of H. pylori eradication therapy on TL. Place and Duration of Study: This is a seven months case- control study conducted in Hepatology, Gastroenterology and Infectious Diseases and Medical Microbiology & Immunology Departments, Benha University, Egypt. Methodology: Relative TLs in gastric mucosa were analyzed by Real Time-Polymerase Chain Reaction (RT-PCR) in 15 H. pylori -positive patients (Group I: 10 patients with gastric ulcer, Group II: 5 patient without gastric ulcer) and 10 H. pylori -negative controls (Group III). Relative TLs were re-evaluated in H. pylori-positive patients 4 weeks after H. pylori eradication therapy. Results: Highly significant shortening (P