In 43 cases of adenoid cystic carcinomas of the salivary glands (ACC), expressions of the oncogene products such as epidermal growth factor receptor (EGF-R), erbB-2 product, c-myc product and N-myc product were investigated immunohistochemically. First, we confirmed the specificity of the antibodies used with the 13 cell lines. Of the anti-EGF-R antibodies, clone 29. 1. 1 reacted only with A431 but not with the other cell lines overexpressing EGF-R, so that it was most likely to cross-react with the blood type A antigen. Also, the anti-N-myc product antibody revealed the presence of a certain cross-reacting antigen in Lu65. Overexpression of EGF-R was observed in only one case. Nine cases (20.9%) showing tubular and cribriform patterns overexpressed the erbB-2 product, but the signals were mainly localized in the cytoplasm as a granular appearance. Eighteen cases (41.9%) with slight cellular atypia showed an overexpression of the c-myc product. The immunolocalization of the c-myc product was at the nuclei in most cases, or both the nuclei and the cytoplasm in some cases. None of the ACC expressed the N-myc product. It is speculated that the multiple oncogene expressions might be partly related to the acquirement of the differentiated or malignant phenotype in the ACC.