Recent studies have shown that women with invasive breast carcinoma having high microvessel density (MVD) (a measure of tumor angiogenesis) or epidermal growth factor receptor (EGFR) expression have increased risk for metastasis and/or decreased survival. To determine if MVD and EGFR expression provide additive prognostic information, we analyzed these two prognostic indicators in the primary invasive breast carcinomas from 165 consecutive patients, who were followed for a median of 51 months. Univariate analysis showed a highly significant (p < 0.001) association of MVD with overall and relapse-free survival in all patients, including both node-negative and node-positive groups (see JNCI 84:1875-1887, 1992). For EGFR, although univariate analysis suggested that women with tumors showing EGFR expression relapsed earlier and, perhaps, died earlier, the differences were not statistically significant. Multivariate analysis, in contrast, revealed that determination of EGFR did provide significant additional information to that already provided by MVD for predicting relapse-free survival in all women (p = 0.001) and in the subset of node-positive women (p = 0.007). Among node-negative women, however, the contribution of EGFR expression in predicting relapse-free survival was not significant (p = 0.12). Likewise, EGFR measurement did not provide significant additional information beyond that of MVD alone for predicting overall survival. Thus, EGFR provides additional prognostic information to determination of MVD, but only for relapse-free survival in node-positive women with invasive breast carcinoma.