In a retrospective study, immunohistochemical determinations of p53 were performed on paraffinised tissue sections of 243 patients with node negative breast cancer. These patients were primary treated in the years 1980-1986 at the UFK-Würzburg. A complete follow up could be performed in 92% of all cases. The median follow up is at 102 month. The results have been correlated to other prognostic criteria and to the clinical course of the patients. In 77 of the 243 cases a positive immunohistochemical staining for p53 (31.7%) could be found. In 42 (17.3%) cancer specimens the p53 expression was over 5%. A significant correlation was found between p53 and tumour size (p = 0.05), ploidy (p < 0.001) and dynamic parameters of the cell cycle (S-phase-fraction, MIB1: p < 0.001). In univariate and multivariate analysis the expression of p53 did not effect disease-free or over-all survival of patients with node negative breast cancer.