The purpose of this study was to show the immunohistochemical activity of the commercialized antibodies of oncogene products and related enzymes using extremely small lesions of tubular adenocarcinomas in human stomachs. Seven lesions among 11 carcinoma lesions (63.6%) measuring 1mm in diameter and 8 among 8 carcinoma lesions (100%) measuring 1∼5mm in diameter showed positive reaction in their cytoplasms for c-myc oncogene products (6E10). In immunohistochemical staining for c-erbB-2 gene product no carcinoma lesions (0%) measuring 1mm in diameter were positive in their cytoplasms and all carcinoma lesions (100%) measuring 1∼5mm in diameter were positive in their cytoplasms. One lesion (1/11 lesions, 9.1%) measuring 1mm in diameter and 6/8 lesions (75%) showed positive reactions in their cytoplasms for protein kinase C (Type III) immunohistochemically (x2 analysis, p<0.05). All gastric minute tubular adenocarcinoma lesions in this study were positive in their cytoplasms for lysozyme immunohistochemically.