Breast cancer is the most frequent gynecological tumor. The HER-2/neu oncogene may play a role in the prognosis and management of patients with breast cancer. In a retrospective study on 100 patients, we correlated the expression of this oncogene with the classic clinical and pathological factors. 32 % of patients exhibited overexpression of HER-2/neu. There was no significant correlation with classic parameters. This finding could indicate that HER-2/neu expression is a new independent prognostic factor. Prospective studies correlating HER-2/neu overexpression with prognosis might provide additional data.