Objective: To investgate changes of 5-HT and gastrin cells (G cells) in human antral mucosa during peptic ulcer. Methods: The 5-HT cells and G cells were stained with PAP double stainings on the same section. Results: The 5-HT cells were mainly distributed in mid-below third of the mucosa.The cells were brown-yellow.5-HT cells were varied in shape and most of them had long processes. The G cells were located in midzone of the mucosa. Most of them were blue and a few were bluish-yellow. The G cells appeared in different shapes such as spheroid and pyramid. The number of 5-HT cells and G cells were 4.25±1.20

7.79±2.11 in gastric ulcer (Gu)group; 5.48±1.74

9.34±1.87 in duodenal ulcer(Du) group ; 3.17±1.65

6.08±1.67 in control(Con) group respectively. The numbers of 5-HT cells and G cells in gastric ulcer and duodenal ulcer were higher and showed significant difference from those of the control group respectively. Conclusion: It is suggested that 5-HT cells and G cells may participate in the endocrine regulation during peptic ulcer.