Background: The gastric restrictive operations are the gold standard for obesity surgery, but, little is known about the 
histological changes that occur in the distal pouch of the stomach and pyloric antrum. 
Methods: The present study was conducted on 33 adult New Zealand Albino rabbits randomly classified into 3 groups. Group A, comprised 3 rabbits underwent laparotomy only (control group). Group B, comprised 15 rabbits underwent vertical banded gastroplasty.. Group C, comprised 15 rabbits underwent gastric partition and bypass operation. 
Results: On gross examination, by laparotomy, at the end of the second and fourth weeks, there was no change in the size of the stomach with minimal adhesions between it and the surroundings in group A (control group), and extensive adhesions in groups B and C. But after six weeks there was an increase in the proximal small gastric pouch (by 1-3 ml, a mean of 1.9 ml) in group C only. On histopathological examination using light and scanning electron microscopy, the proximal small gastric pouch in groups B and C, showed hemorrhagic patches in mucosa, submucosa and musculosa and loss of surface epithelial cells, which disappeared after 4 weeks. The distal gastric pouch and pyloric antrum 4 weeks after the operation showed nuclear hyperchromatosis of the lining mucosal cells, loss of normal mucosal glandular architecture,and scattered areas of mucosal necrosis. Six weeks after the operation, we found, scattered areas of squamous metaplasia, intestinal metaplasia with goblet cells, and areas of surface epithelial hypertrophy in groups B and C only. 
Conclusion: The gastric restrictive operations produce histopathological changes in the distal pouches of the stomach and pyloric antrum, varying from gastritis up to intestinal metaplasia. So it is preferable to indicate the operations only in few patients, where morbid obesity is a pathological state and is very difficult to treat by non-surgical means. Long term follow up study is needed to prove the possibility of malignant transformation in these metaplastic tissues.