Invasive breast carcinomas of 19 premenopausal and 49 postmenopausal women were studied by Southern blot analysis for detection of c-erbB2 and int-2 oncogenes, and quantitation of c-erbB2 protein, p185 by ELISA. The data were correlated with the histological grade of the tumor and the patient's clinical status. Seventeen tumors (25.0%) showed genomic alteration in one or both oncogenes. c-erbB2 and int-2 amplification were expressed by 10 (14.7%) and 7 (10.2%) of the tumors respectively. c-erbB2 overexpression was found in 15 out of 68 tumors (22.1%). All tumors exhibiting amplification of c-erbB2 also showed overexpression of p185 protein, however 5 out of 15 tumors (33.3%) showing c-erbB2 overexpression did not show amplification. Rearrangement of c-erbB2 and int-2 oncogenes was observed in 4 out of 68 tumors (5.9%) and 2 of these tumors presented rearrangement of both oncogenes. A significant positive correlation was found between c-erbB2 amplification and p185 protein overexpression, and c-erbB2 and int-2 amplification. Oncogene alterations were more frequently detected in tumors with high histological grade, but no correlation was found with patient's age, menopausal or lymph node status.