More than 18,000 serial sections were performed in 10 ulcer-bearing gastrectomy specimens with mild intestinal metaplasia and containing minute lesions of intestinal metaplasia composed of a few metaplastic tubules, which often had an onion skin-like appearance. Fifty-two minute lesions could be reconstructed and examined three-dimensionally in these serial sections. As a result of this study, these minute lesions showed, without exception, a very close resemblance to a hen's egg or globe and had a dimple at the center. Moreover, we could detect minute lesions of intestinal metaplasia in which erosion and indifferent epithelia coexisted. From the various circumstantial findings, it was demonstrated that these lesions originated in the regenerative process of erosions.