The c-erbB-2 oncogene has been shown to be amplified in a variety of human adenocarcinomas. Antibodies to the protein product, p185, have been used for immunostaining of paraffin-embedded material, and have demonstrated that high levels of c-erbB-2 protein expression correlate with gene amplification under certain conditions. In studies by others, amplification has been demonstrated in 40 per cent of tubular type adenocarcinomas of the stomach, and an immunohistochemical study on frozen tissue has demonstrated staining in 3 out of 10 cases. Our study, using paraffin-embedded material, demonstrates staining in 19 per cent of 126 cases using a polyclonal antibody. Of the positive cases, 75 per cent were tubular or papillary type (P less than 0.025), and prominent staining was restricted to this group. Three cases showed well-defined positive areas in keeping with clonal expression of p185. No specific staining of normal or dysplastic epithelium adjacent to the carcinomas was found.