The tyrosine kinase receptor family, including the epidermal growth factor receptor (EGF-R), c-erbB2 and, more recently, the c-erbB3, has been recognized as being of particular importance in many human malignancies. This study was undertaken to define the role of c-erb B2 and c-erbB3 in adenoid cystic carcinomas (A.C.C.) of the salivary glands. Sixteen cases of A.C.C. were studied immunohistochemically, using antibodies against each erbB gene family product. EGF-R was not detected in any of these samples but c-erbB2 and c-erbB3 gene products (ERBB2and ERBB3) were demonstrated in all A.C.C. sections with some degree of straining. Tubular and cribriform patterns overexpressed particularly large amounts of ERBB2 and ERBB3. Strong staining was mainly demonstrated in tumor cells of the invasive area. These results suggested that overexpression of ERBB2 and ERBB3 is related to tumor differentiation and invasion in adenoid cystic carcinomas.