The presence of transforming growth factor-alpha (TGF-alpha) was studied in a total of 120 consecutive patients with gastric carcinomas. This immunohistochemical study found TGF-alpha expression in 60% (n = 72) of carcinomas. It also was detected in normal gastric epithelial mucosa in 36% (n = 43) of specimens. There was no significant statistical correlation between TGF-alpha expression and clinical features (e.g., patient age and sex) or pathologic features (e.g., tumor stage, grade, and localization or growth pattern according to an earlier histologic classification). Expression of TGF-alpha by these tumor cells had no influence on prognosis. It was neither a histopathologic marker of high malignancy nor a useful prognostic tool. It had no influence on the invasive growth pattern of gastric carcinoma.