One hundred and sixty-two breast carcinomas treated by adjuvant chemotherapy were investigated in immunohistochemistry for expression of p53 and two wild-type p53-regulated induced proteins, mdm2 and p21/waf1. p21 and mdm2 were expression stongly correlated with Ki67 but not with survival. The p53+/p21+, p53+/p21- and p53+/mdm2- phenotypes were associated with the worst prognosis. The p53+/p21+/ mdm2+ tumors were associated with a better outcome than the other phenotypes, they may be tumors expressing wild-type p53 and p21, and a form of mdm2 that might lead to the stabilization of p53. It is suggested that p21/mdm2 expression should be investigated in all cases of p53 positive breast cancer.