Insight into correlations between specific gene amplification and the clinical behavior of tumors may provide new prognostic tools High c-erbB-2 expression is an early feature in some breast tumors, whereas c-myc may be involved in the development of neoplasia. After an initial flurry of excitement about their prognostic significance, controversy has arisen about their independent importance. In an attempt to solve this problem, we decided to study c-erbB-2 and c-myc amplification and overexpression in 62 unselected breast carcinomas. This was done in order to correlate them statistically with one another, as well as with other prognostic parameters. A positive correlation was discovered between c-erbB-2 amplification and overexpression (P = 0.02); however, the correlations between c-erbB-2 amplification and c-myc amplification and overexpression (P = 0.06 and P = 0.095 respectively) were found to be negative. In addition, no correlation was found to exist between c-erbB-2 amplification and Cathepsin-D, steroid receptors, node status and menopausal status, as well as between c-erbB-2 overexpression and Cathepsin-D, node invasiveness, tumor status, grade or menopausal status. In conclusion, the c-erbB-2 overexpression has positive correlation with only a few other prognostic parameters, and therefore can be used as an independent prognostic factor.