In this immunohistochemical study we investigated the expression of Bcl-2 and Bax apoptosis related proteins in node-negative breast carcinomas. The results were correlated with the recurrence rate of the patients. In order to avoid the influence of the most important tumor prognostic parameters we selected two groups of node negative breast ductal carcinomas that were grade II according to Bloom and Richardson classification, had a diameter of 1-3 cm but differed in clinical outcome: 44 of the patients had a 10 year disease-free survival while 46 developed metastatic disease in the same period of time. Bcl-2 and to a lesser degree Bax expression were inversely related with distant metastases (Pbcl-2 = 0.007, Pbax = 0.03). Combined analysis of Bax/Bcl-2 expression in relation to clinical outcome showed that the absence of both factors was more strongly associated with the development of distant metastases (P = 0.006, Ptrend = 0.001). Our findings indicate that Bcl-2 and Bax apoptosis-related proteins are good indicators of prognosis in node-negative breast cancer patients, and their combined absence, suggestive of serious deregulation of the apoptotic process, may contribute to the biologic aggressiveness of the tumors.