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.(ABSTRACT TRUNCATED AT 250 WORDS)