Because zinc is one of the most important trace elements in humans and is involved in growth and repair of multiple tissues. In this study, we investigated whether changes in serum and duodenal tissue zinc levels were present in patients with duodenal ulcer disease. For this, 17 patients with duodenal ulcers and 16 controls undergoing upper gastrointestinal endoscopy for symptoms of abdominal discomfort were prospectively studied. Endoscopy was normal in controls. Blood was taken to measure serum zinc concentrations prior to endoscopy and tissue zinc levels were measured in tissue obtained by biopsy from the margins of an ulcer or from the bulbus in controls. Serum zinc concentrations were not different in patients with duodenal ulcers compared to the control group (68.6 ± 10.4 μg/dl vs 72.3 ± 8.7 μg/dl respectively, p>0.05). Tissue zinc concentrations were significantly higher in patients with duodenum ulcer compared to controls (40.4 ± 14.3 μg/gr tissue vs 32.5 ± 7.7 μg/gr tissue, p<0.05). This study suggests that in ulcer patients: (1) greater amounts of zinc are concentrated in the rapidly proliferating duodenal ulcer tissue, (2) the serum zinc pool may serve as a major zinc source.