Cytogenetic analyses were performed on a short-term culture of a primary tumor and an established cell line of gastric adenocarcinoma (SC-M1). The former case was near-diploid, and the latter was near-triploid. No common numerical and structural change or breakpoint was found in these cells. Review of the 13 cases of gastric carcinomas so far reported showed that only trisomies 8 and 9 were consistent findings. The Y chromosome, although lost in all the near-triploid cases, was preserved in all of the near-diploid cases. No consistent structural abnormality and breakpoint were identified in this and other studies.