Objective: To investigate the association of changes in G and D cells in the antral mucosa with the production of gastrin and somatostatin during gastric ulcer and the healing process. Methods: Experimental gastric ulcer was induced with acetic acid in 42 Wistar rats and another 7 normal rats served as control.Changes in the production of gastrin and somatostatin in the plasma, gastric fluid and the antral tissues of the rats were measured by radio immunoassay, and the number and distribution of G and D cells were respectively determined by immunochemistry and Quantimet500 image analysis system. Results: In rats with gastric ulcer, the gastrin levels in the plasma, gastric fluid and the antral tissues increased while somatostatin levels were reduced, which were corrected in the healing process. Immunochemistry demonstrated the increase in the number of G cells in the antral tissues with decrease in D cell number, and the area covered by both cells shrank. The G cell to D cell number and area ratios were both decreased after the onset of the ulcer and reted to the normal when the healing process took place. Conclusion: Secretion of gastrin by G cells increases and that of somatostatin by D cells declines during gastric ulcer in rats, and imbalance of G and D cells may be restponsible for gastrointestinal dysfunction.