Prompted by recent findings on the amplification of c-erbB-2 (HER-2, neu) oncogene in salivary gland tumours, the present study was conducted to analyse the expression of c-erbB-2 in both benign and malignant salivary gland tumours, with special emphasis on its prognostic significance and relevance to clinical data. A series of 219 salivary gland tumours (with pertinent clinical data), including 103 malignant and 116 benign tumours, were analysed immunohistochemically using a monoclonal antibody to c-erbB-2 protein. Smoking was not a risk factor for malignant tumours, smokers being equally represented in both groups: 18.4 and 21.6% in malignant and benign series, respectively. Multi-variate analysis of the extensive clinical data did not disclose any other risk factors either. Cellular membrane staining for c-erbB-2 was present in 36 (35.0%) carcinomas and 41 (35.3%) benign tumours. Among the malignant tumours, c-erbB-2 expression was most frequent in adenoid cystic carcinomas (57.7%) followed by adenocarcinomas (39.3%). Among the benign tumours, 47% of Warthin’s tumours and 33.3% of the pleomorphic adenomas showed staining for c-erbB-2. The highest prevalence of c-erbB-2 immunoreactivity was seen in adenocarcinomas of the parotid gland (81.8%), followed by undifferentiated carcinomas (75%) and adenoid cystic carcinomas (73.3%) in that location. Age at diagnosis, number of recurrences, analysis as well as time to relapse or metastases were similar in c-erbB-2-positive and -negative malignant tumours. Also mortality in c-erbB-2-positive and -negative salivary gland cancers was similar. The results indicate that c-erbB-2 protein expression is frequently present in both malignant and benign salivary tumours. Although weakly associated with some clinically relevant parameters, the expression of this oncoprotein seems to be of limited use as a prognostic determinant in salivary gland tumours.