Histopathological and immunohistochemical findings on tissue microarrays, overall survival (OS), disease-free survival (DFS) and incidence of relapses (R) were recorded and statistically analyzed in 289 breast cancers. A higher R and a shorter DFS were significantly related to larger tumors, lymph node invasion, higher tumor grade, absence of estrogen receptors (ER), triple negative tumors, and presence of lymphovascular invasion (LVI). Longer OS was observed to be significantly associated with smaller tumor size (T), lymph node negativity, lower tumor grade, absence of LVI, lower Mib-1 expression and with the presence of ER. At multivariate analysis, only T for DFS and lymph node status and triple negativity either for DFS or OS had independent prognostic value. In the 194 lymph node-negative women DFS and OS were inversely related to tumor grade, absence of ER, Mib-1 expression in more than 15% of neoplastic cells and, only for DFS, presence of LVI. In the 95 lymph node-positive the number of involved nodes was the most discriminating parameter either for DFS or OS; T, Her-2 status and presence of LVI were significantly related to DFS. ER negativity was related to higher grade, progesterone receptors (PR) negativity, Her-2 negativity, hence to triple negativity, to basal-like type, Mib-1expression over 15% of neoplastic cells. Her-2 positivity was related to higher grade, ER positivity and PR positivity. Basal-like type was not an independent prognosticator, while triple negative type has a significant relation to shorter OS. The Nottingham prognostic index accurately identifies prognostic groupings and Mib-1 expression and ER signaling are the key biological predictors even in single cases.